More than 400 essential computer terms, from hardware and software to networks, programming, databases, cyber security and AI, each with a clear definition and a real-life example.
"What does bandwidth mean?" "What is the difference between RAM and ROM?" "What is a compiler?" Every day, students search for the meaning of computer words, and the answers are often scattered across many pages, written in a hard-to-follow style, or missing the one example that makes the idea click. This guide gathers 416 essential computer terms in one place, from the very first words you meet (hardware, software, data) to more advanced ideas such as encryption, recursion, neural networks and cloud computing. Each term has a clear definition and a real-life example. You can search for a word, jump from the A–Z index, or read a whole topic at a time.
A definition says what a word means. An example shows the idea in action. Together they are the quickest way to learn technical vocabulary, because the definition gives the exact meaning and the example gives you a picture to remember. The topics move from basic to advanced, but you may read them in any order.
Showing all 416 terms.
Before the long list, look at three simple diagrams. They connect dozens of the terms below into a bigger picture.
Every computer, from a phone to a supercomputer, follows the same four-step pattern: it takes in input, processes it, gives output, and stores data for later.
All data in a computer is stored as bits. Larger units are built by grouping bits and bytes, and each step up multiplies the size by about one thousand.
When you type a web address, many of the terms in this guide work together: the browser, DNS, IP addresses, the router, your ISP, and a web server.
The physical machine: what a computer is, what its parts are called and what each part does.
An electronic machine that accepts data (input), processes it by following instructions, stores it, and produces results (output).
Example: A laptop turns the keys you press into a typed document on the screen.
The physical parts of a computer that you can see and touch.
Example: Monitor, keyboard, mouse, motherboard and the case are all hardware.
Programs and instructions that tell the hardware what to do. You cannot touch software.
Example: A web browser, a word processor and a game are all software.
Raw facts, figures or symbols that have no meaning on their own until they are processed.
Example: The numbers 35, 42 and 58 in a list of test marks.
Data that has been processed or organised so that it has meaning and is useful.
Example: "The class average is 45" is information made from the list of marks.
Hardware that sends data or commands into a computer.
Example: Keyboard, mouse, scanner, microphone and webcam.
Hardware that shows or delivers the results of processing to the user.
Example: Monitor, printer and speakers.
Any device connected to a computer that is not part of its core (processor and memory).
Example: A printer, an external hard drive or a webcam.
The main chip that carries out the instructions of programs. It is often called the "brain" of the computer.
Example: The processor chip inside a laptop that runs your apps.
The part of the CPU that performs arithmetic (such as add and subtract) and logic (such as compare) operations.
Example: Working out 7 + 5, or checking whether 9 is greater than 4.
The part of the CPU that directs the flow of instructions and data, by fetching each instruction, decoding it and telling other parts what to do.
Example: It fetches the instruction "add these two numbers" and signals the ALU to do it.
A tiny, extremely fast storage location inside the CPU that holds the data or instruction being used right now.
Example: The register holding a number while the ALU adds it to another number.
A small, very fast memory close to the CPU that keeps frequently used data so the CPU waits less.
Example: The L1, L2 and L3 caches built into a modern processor.
The number of cycles the CPU's clock completes each second, measured in hertz (Hz). A higher value usually means faster work, but it is not the only thing that decides performance.
Example: A 3.5 GHz processor ticks 3.5 billion times a second.
An independent processing unit inside a CPU. A multi-core CPU can work on several tasks at the same time.
Example: A quad-core CPU has four cores.
The main circuit board that connects the CPU, memory, storage and other components so they can communicate.
Example: The RAM sticks, CPU and graphics card all plug into the motherboard.
Fast, temporary memory that holds the programs and data currently in use. Its contents are lost when the power is switched off.
Example: Your open documents and browser tabs sit in RAM.
Memory that keeps its contents without power and is normally only read, often storing the start-up instructions of a device.
Example: The chip that stores the firmware used to start a computer.
Firmware stored on the motherboard that tests the hardware at power-on and then loads the operating system. UEFI is the modern replacement for the older BIOS.
Example: Pressing a key at start-up to open the setup screen and change the boot order.
A processor designed to do many calculations at once, mainly for images, video, games and AI.
Example: The chip that draws the 3D scenes of a game.
A circuit board added to a slot on the motherboard to give a computer extra features.
Example: A graphics card or a network card.
The part that converts mains AC electricity into the lower DC voltages that computer components need.
Example: The metal box with a power cable at the back of a desktop computer.
A socket on a computer where a cable or device is connected.
Example: USB, HDMI, Ethernet and headphone ports.
A standard connection used to attach peripherals, transfer data and charge devices.
Example: Plugging a flash drive into a laptop.
A connection that carries digital video and audio at the same time, mostly to monitors, projectors and TVs.
Example: Connecting a laptop to a classroom projector.
An output device with a screen that displays text, pictures and video from a computer.
Example: An LED monitor on a desk.
The smallest dot of colour on a screen or in a digital image (short for "picture element").
Example: A Full HD screen of 1920 × 1080 pixels has 2 073 600 pixels.
The number of pixels in an image or display, usually given as width × height. More pixels allow finer detail.
Example: 1920 × 1080 is called Full HD.
An input device with keys used to enter text, numbers and commands. The common QWERTY layout is named after the first six letters on its top letter row.
Example: Typing an essay.
A pointing input device that moves a pointer on the screen and lets you click, drag and scroll.
Example: Clicking an icon to open a program.
A display that is also an input device, because it detects touch from a finger or stylus.
Example: Tapping an app on a smartphone.
An output device that produces text or pictures on paper. An inkjet printer sprays tiny drops of ink; a laser printer uses a laser to fix toner powder onto the page with heat.
Example: Printing a homework sheet.
An input device that converts a paper document or photograph into a digital image or file.
Example: Scanning a certificate to save it as a PDF.
A device that detects a physical change such as light, temperature, pressure or movement and turns it into an electrical signal.
Example: The accelerometer that rotates a phone screen when you turn the phone.
A small computer built into a device to do one specific job, usually with little or no user interface.
Example: The controller inside a microwave oven or a washing machine.
How computers measure, keep and organise data.
The smallest unit of data in a computer: one binary digit, either 0 or 1.
Example: A switch that is either off (0) or on (1).
A group of 8 bits. It is the usual unit for storing one character.
Example: The letter "A" is stored in one byte as 01000001.
About one thousand bytes. In the SI system and on storage packaging 1 KB = 1000 bytes; in some computing contexts 1 KB = 1024 bytes (the exact binary unit is the kibibyte, KiB).
Example: A short plain-text email is a few kilobytes.
About one million bytes (1000 KB, or 1024 KiB in binary counting).
Example: A typical phone photo is a few megabytes.
About one billion bytes (1000 MB).
Example: A standard-definition film may take 1 to 2 GB; a phone might have 128 GB of storage.
About one trillion bytes (1000 GB).
Example: A 1 TB drive holds roughly 250 films of 4 GB each.
Memory the CPU can reach directly. It includes RAM, ROM and cache, and it is fast but limited in size.
Example: The RAM that holds a running program.
Long-term, non-volatile storage that keeps data when the power is off. It is slower but larger and cheaper per gigabyte than primary memory.
Example: A hard drive, SSD, USB flash drive or memory card.
Memory that loses its data when the power is switched off.
Example: RAM.
Memory that keeps its data even when the power is switched off.
Example: ROM, SSDs and flash drives.
Space on a storage drive that the operating system uses as extra "pretend" RAM when the real RAM is full. It is much slower than real RAM.
Example: The page file on Windows or swap space on Linux.
A storage device that records data magnetically on spinning discs (platters) read by a moving head. It is cheaper per gigabyte but slower and more easily damaged by knocks than an SSD.
Example: The large-capacity drive in an older desktop computer.
A storage device that uses flash memory chips and has no moving parts. It is faster, quieter and more shock-resistant than an HDD.
Example: A laptop that starts up in a few seconds.
A small, portable storage device that uses flash memory and plugs into a USB port.
Example: Carrying a presentation to school on a flash drive.
A small flash-memory card used to store data in cameras, phones and other devices.
Example: An SD card in a camera.
A disc whose data is read by a laser. Common types are CD (about 700 MB), DVD (4.7 GB per layer) and Blu-ray (25 GB per layer).
Example: A movie on a DVD.
A copy of data kept in a separate place so that it can be restored if the original is lost, damaged or stolen. A common rule is 3 copies, on 2 different types of storage, with 1 copy kept away from the main location.
Example: Copying your school project to an external drive and to cloud storage.
A named collection of related data stored on a device.
Example: essay.docx or holiday.jpg.
A container used to organise files and other folders.
Example: A folder called "Homework" containing one folder for each subject.
The letters after the final dot in a file name that show the type of file.
Example: .jpg for pictures, .pdf for documents, .mp3 for audio, .docx for Word files.
The way the data inside a file is organised so that a program can read it.
Example: JPEG, PNG, PDF and MP4 are file formats.
Making a file smaller by storing its data more efficiently. This saves space and speeds up transfers.
Example: Zipping a folder before emailing it.
Compression that allows the exact original data to be restored.
Example: ZIP files and PNG images.
Compression that permanently removes some detail to achieve a much smaller file.
Example: JPEG photographs and MP3 music.
Preparing a storage device for use by creating a file system on it. It usually erases the existing data.
Example: Formatting a new memory card in a camera.
A section of a drive that is treated as a separate drive.
Example: One physical disk shown as drive C: and drive D:.
Rearranging the scattered pieces of files on a hard disk so that each file is stored together, which makes reading faster. It is not needed for SSDs.
Example: Running a defragmentation tool on an old HDD.
The programs that make a computer useful, and the system that manages everything.
Software that controls and manages the computer hardware and provides a platform for other software.
Example: An operating system or a device driver.
Programs designed for users to carry out a specific task.
Example: A word processor, web browser, calculator app or game.
System software that manages the hardware, memory, files and programs, and provides the interface between the user and the computer.
Example: Windows, macOS, Linux, Android and iOS.
System tools that help to maintain, protect or optimise a computer.
Example: Antivirus, backup tools, disk cleaners and file compressors.
A small program that lets the operating system communicate with a hardware device.
Example: A printer driver installed so that a computer can print.
Permanent software stored in a hardware device's non-volatile memory that controls its basic operation.
Example: The software inside a router or a TV remote.
The core part of an operating system that manages the CPU, memory and devices, and sits between software and hardware.
Example: The Linux kernel.
A way of using a computer through windows, icons, menus and a pointer instead of typing commands.
Example: The Windows desktop or a phone home screen.
A way of using a computer by typing text commands.
Example: Typing a command in a terminal to list the files in a folder.
The ability of an operating system to run several programs at the same time, by switching quickly between them or using several cores.
Example: Listening to music while writing a document.
A program that is currently running in memory.
Example: Each open application is at least one process.
The start-up sequence in which the computer tests its hardware and loads the operating system into RAM.
Example: Turning on a PC and waiting for the login screen.
Using software to create a virtual (software-based) version of a computer, storage or network, so one physical machine can act as several.
Example: Running a Linux virtual machine on a Windows laptop.
A software-based computer that runs inside a real computer and behaves like a separate machine.
Example: Testing a program in a safe, separate environment.
Software whose source code is freely available for anyone to view, use, change and share under a licence.
Example: Linux and the Firefox browser.
Software owned by a company or person who controls the source code and sets the rules for its use.
Example: Microsoft Windows and Adobe Photoshop.
Software that can be used free of charge, but whose source code is usually not shared.
Example: A free PDF reader.
A legal agreement that sets out how software may be used, copied and shared.
Example: The "I agree" terms you accept when installing a program.
The process of copying a program onto a computer and setting it up so that it can be used.
Example: Installing an app from an app store.
A new version or improvement of a program that adds features or fixes problems.
Example: The monthly system update on a phone.
A small update that fixes a specific bug or security hole.
Example: An emergency patch for a newly found security flaw.
A mistake or fault in a program that makes it behave in an unexpected way.
Example: A calculator that shows 2 + 2 = 5 because of a coding mistake.
A version of software released for testing before the final release, so that users can report problems.
Example: A beta of a new game offered to volunteers.
A program that translates all the source code of a high-level language into machine code before the program runs.
Example: Translating C++ code into an .exe file.
A program that translates and runs source code line by line, without making a separate machine-code file first.
Example: Python code is usually run by an interpreter.
A program that translates assembly language into machine code.
Example: Turning the instruction ADD into binary for the CPU.
A free, open-source operating system family based on the Linux kernel; it is widely used on servers, supercomputers and Android devices.
Example: Ubuntu and Debian.
A family of operating systems made by Microsoft, with a graphical desktop, widely used on personal computers.
Example: Windows 11.
The operating system made by Apple for its Mac computers.
Example: Running macOS on a MacBook.
An operating system for smartphones and tablets, based on the Linux kernel and developed by Google.
Example: Most non-Apple smartphones.
The operating system made by Apple for the iPhone.
Example: Installing apps on an iPhone from the App Store.
Short for application: a program, especially one for a phone or tablet.
Example: A messaging app.
Software that works on more than one type of operating system or device.
Example: A browser available on Windows, macOS and Android.
How computers store numbers, text, pictures and sound using only 0s and 1s.
A base-2 number system that uses only the digits 0 and 1. Computers use it because electronic circuits have two states, on and off.
Example: The binary number 1011 equals 11 in decimal (8 + 0 + 2 + 1).
The everyday base-10 number system that uses the digits 0 to 9.
Example: The number 345 means 3 hundreds, 4 tens and 5 units.
A base-16 number system that uses the digits 0 to 9 and the letters A to F. Each hex digit stands for exactly 4 bits, so it is a short way to write binary.
Example: FF in hexadecimal is 255 in decimal; the colour code #FF0000 means full red.
A base-8 number system that uses the digits 0 to 7. Each octal digit stands for 3 bits.
Example: Used for file permissions on Linux, for example 755.
A character code that gives numbers to 128 letters, digits and symbols, so text can be stored as numbers.
Example: The capital letter A is stored as 65 and the lower-case a as 97.
A universal standard that gives a unique code to the characters of almost all of the world's writing systems, plus symbols and emoji.
Example: Urdu, Chinese and emoji can all be stored using Unicode.
A very common way of encoding Unicode, using 1 to 4 bytes per character. The first 128 characters match ASCII.
Example: Most web pages are encoded in UTF-8.
The collection of characters that a system can recognise and represent.
Example: ASCII is a small character set; Unicode is a very large one.
The number of bits used to store the colour of each pixel. More bits allow more colours.
Example: A 24-bit image can show 16 777 216 colours.
A way of making colours by mixing Red, Green and Blue light. Screens use it.
Example: Red + green light makes yellow on a screen.
An image made of a grid of pixels. Enlarging it too much makes it look blocky.
Example: A JPEG or PNG photograph.
An image made from mathematical shapes such as lines and curves. It can be enlarged without losing quality.
Example: An SVG logo that stays sharp on a billboard.
The number of times per second that a sound wave is measured when sound is digitised, in hertz (Hz).
Example: Music CDs use 44 100 samples per second (44.1 kHz).
An extra bit added to a group of bits so that the total number of 1s is always even (even parity) or always odd (odd parity). It lets the receiver detect a single-bit error.
Example: With even parity, the data 1011 has three 1s, so the parity bit is 1 and the sent group 10111 has four 1s.
A value calculated from a block of data and used to check that the data has not been changed or damaged.
Example: Comparing the checksum of a downloaded file with the one on the website.
An error that happens when a calculation produces a number too big to be stored in the number of bits available.
Example: Adding 1 to 255 in an 8-bit store gives 256, which does not fit.
The most common method for representing negative whole numbers in binary.
Example: In 8-bit two's complement, -1 is stored as 11111111.
A way of storing numbers with a fractional part, using a mantissa (digits) and an exponent (where the point goes).
Example: 3.14159 is stored approximately.
A value or type with only two possible values: true or false.
Example: isLoggedIn = true.
A tiny electronic circuit that performs a basic logical operation on one or more binary inputs and gives one output.
Example: AND, OR and NOT gates.
A logic gate whose output is 1 only when all of its inputs are 1.
Example: Inputs 1 and 0 give 0; inputs 1 and 1 give 1.
A logic gate whose output is 1 when at least one input is 1.
Example: Inputs 1 and 0 give 1.
A logic gate that outputs the opposite of its single input.
Example: Input 1 gives output 0.
A logic gate that gives the opposite of an AND gate. It is "universal", because any other gate can be built from NAND gates.
Example: Inputs 1 and 1 give 0; every other input pair gives 1.
A logic gate whose output is 1 only when its two inputs are different.
Example: Inputs 1 and 0 give 1; inputs 1 and 1 give 0.
A table listing every possible combination of inputs for a logic circuit and the output for each one.
Example: The four rows of a two-input AND gate.
How computers connect, share data and reach the world.
Two or more computers or devices connected so they can share data, files and resources.
Example: The computers in a school lab sharing one printer.
A network covering a small area such as a room, home, school or office building.
Example: The home Wi-Fi that connects your family's phones and laptops.
A network covering a large area, such as a country or the world, usually by joining many LANs together.
Example: The Internet is the largest WAN.
A network that covers a city or large campus.
Example: A city-wide network linking government offices.
A very small network around one person, usually within a few metres.
Example: A phone connected to wireless earbuds by Bluetooth.
A LAN in which devices connect by radio waves instead of cables.
Example: Wi-Fi in a café.
The worldwide network of connected networks that uses standard protocols to exchange data. It is the infrastructure (cables, routers, servers), not just the web.
Example: Email, video calls and websites all travel over the Internet.
A collection of linked web pages and files that you can reach over the Internet using a web browser. It is a service that runs on the Internet.
Example: Opening a news website.
A private network that uses Internet technology and is available only to members of an organisation.
Example: A school's internal site for staff timetables.
A private network that lets selected outside people, such as customers or suppliers, access part of an organisation's intranet.
Example: A company giving suppliers a login to track orders.
A single document on the web, usually written in HTML.
Example: The "About us" page of a website.
A collection of related web pages under one domain name.
Example: edusambam.com is a website made of many pages.
Software used to find, load and display web pages.
Example: Chrome, Firefox, Edge and Safari.
The full address of a web page or file on the Internet.
Example: https://www.example.com/lessons/page1.html
The readable name of a website that is used instead of its numeric IP address.
Example: example.com
The "phone book of the Internet": a system that translates domain names into IP addresses.
Example: Typing a website name and DNS finding the server's IP address.
A unique number that identifies a device on a network so that data can be sent to it.
Example: 192.168.1.10 (IPv4) or 2001:db8::1 (IPv6).
The older version of the Internet Protocol, which uses 32-bit addresses (about 4.3 billion possible addresses) written as four numbers from 0 to 255.
Example: 192.168.0.1
The newer version of the Internet Protocol, which uses 128-bit addresses, giving a vastly larger number of possible addresses.
Example: 2001:0db8:85a3::8a2e:0370:7334
A unique hardware identifier, 48 bits long, assigned to a network card by its manufacturer.
Example: 00:1A:2B:3C:4D:5E
A device that forwards data between different networks and directs packets along the best route. At home it connects your devices to the Internet.
Example: The box your Internet provider gives you.
A device that connects devices in a LAN and sends data only to the device that needs it, using MAC addresses.
Example: A switch linking the computers in a lab.
A simple device that connects devices in a LAN and sends incoming data to all other devices, so it is less efficient than a switch.
Example: An old office network hub.
A device that converts digital data into signals that can travel over telephone, cable or fibre lines, and back again.
Example: A DSL or cable modem.
A device that lets wireless devices connect to a wired network.
Example: A ceiling-mounted Wi-Fi unit in a school.
A wireless networking technology (based on the IEEE 802.11 standards) that connects devices to a network using radio waves.
Example: Connecting a phone to the school Wi-Fi.
The most common standard for wired LANs, using cables to connect devices.
Example: A cable connecting a PC to a switch.
A short-range wireless technology for connecting nearby devices, typically within about 10 metres.
Example: Wireless headphones.
The hardware that lets a computer connect to a network, wired or wireless.
Example: The Wi-Fi chip in a laptop.
A set of agreed rules for how data is formatted, sent and received, so that different devices can communicate.
Example: HTTP, TCP and IP are protocols.
The suite of protocols that runs the Internet. IP addresses and routes the packets; TCP makes sure they arrive complete and in order.
Example: Loading a web page involves TCP/IP.
HTTP is the protocol used to transfer web pages. HTTPS is the secure version, which encrypts the data between your browser and the website.
Example: A padlock beside the address shows that HTTPS is being used.
A protocol for uploading and downloading files between computers over a network.
Example: Uploading website files to a web host.
SMTP sends email. POP3 and IMAP retrieve it; IMAP keeps messages on the server so that you can read them on several devices.
Example: A phone and a laptop both showing the same inbox.
A small piece of data into which a message is divided for sending over a network. Each packet carries its destination address and a sequence number.
Example: An email is split into many packets that are put together again at the destination.
The maximum amount of data that a connection can carry per second, usually in bits per second (bps).
Example: A 50 Mbps Internet plan.
Mbps means megabits per second (how Internet speeds are sold); MBps means megabytes per second. 1 byte = 8 bits, so 8 Mbps is about 1 MBps.
Example: A 40 Mbps line downloads about 5 megabytes each second.
The delay between sending a signal and receiving a response, measured in milliseconds (ms). Low latency matters for gaming and video calls.
Example: A ping of 20 ms is better than 200 ms.
A tool that sends a small test message to another computer and measures how long the reply takes.
Example: Checking whether a server is reachable.
Download means receiving data from another computer; upload means sending data to another computer.
Example: Downloading a video; uploading a photo to a website.
Playing audio or video as it arrives over the Internet, instead of waiting for the whole file to download first.
Example: Watching a lesson on YouTube.
A computer or program that asks another computer (a server) for a service or data.
Example: A web browser requesting a web page.
A computer or program that provides data, services or resources to other computers over a network.
Example: A web server that sends web pages to browsers.
A network design in which clients send requests and a central server responds.
Example: Your browser (client) and a website's server.
A network in which computers share resources directly with each other, without a central server.
Example: Two laptops sharing files directly.
The layout of how devices in a network are connected. Common topologies are bus, ring, star and mesh.
Example: A star topology in a school lab.
A layout in which every device connects to a central switch or hub. If one cable fails, only that device is affected.
Example: The most common layout in homes and offices.
A service that stores a website's files on a server connected to the Internet so that others can view the site.
Example: Paying a company to host a school website.
A company that provides access to the Internet.
Example: A telecom company that sells you a broadband connection.
High-speed Internet access that is always on.
Example: Fibre or DSL home Internet.
A cable of thin glass or plastic strands that carries data as pulses of light, giving very high speed and long distance with little loss.
Example: Undersea cables carry most international traffic.
Cellular networks that give wireless Internet access to phones. 5G is the fifth generation, with higher speeds and lower latency than 4G.
Example: Streaming a video over 5G.
Text or an image that you click to jump to another page, file or part of a page.
Example: Clicking a blue underlined word.
A website that searches an index of web pages and shows a ranked list of results for a query.
Example: Google, Bing and DuckDuckGo.
A small text file that a website stores in your browser to remember information about you or your visit.
Example: A shop remembering the items in your basket.
Software or hardware that monitors network traffic and blocks unauthorised connections according to security rules.
Example: The firewall on a school network blocking unsafe sites.
A server that acts as a middleman between a user and the Internet, which can filter content or hide the user's IP address.
Example: A company proxy filtering websites.
A service that creates an encrypted connection over the Internet, so data is protected and the user's real location is hidden from websites.
Example: Connecting securely to a school network from home.
Technology that carries voice calls over the Internet instead of normal telephone lines.
Example: WhatsApp and Zoom calls.
Electronic mail: messages sent between users over a network.
Example: name@example.com
The vocabulary of writing, testing and sharing code.
A set of instructions that a computer follows to carry out a task.
Example: A calculator app.
A formal language used to write instructions for a computer.
Example: Python, Java, C++ and JavaScript.
The human-readable instructions of a program, written in a programming language.
Example: The text file in which a programmer writes print("Hello").
The binary instructions (1s and 0s) that a CPU can run directly.
Example: The code that results after a compiler translates a program.
A language close to the hardware, hard for humans to read but efficient and fast.
Example: Assembly language and machine code.
A language close to human language, easy to read and write, that must be translated before the computer can run it.
Example: Python and Java.
A low-level language that uses short words (mnemonics) in place of binary instructions.
Example: ADD, MOV and JMP.
The rules that decide how statements must be written in a programming language.
Example: In Python, a missing colon after an if line breaks the syntax.
A step-by-step set of instructions for solving a problem or completing a task.
Example: A recipe, or the steps to find the largest number in a list.
A way of writing an algorithm in plain, structured English, without following the rules of any one programming language.
Example: IF mark >= 50 THEN PRINT "Pass".
A diagram that shows the steps of an algorithm using shapes joined by arrows.
Example: A diamond shape for a yes/no decision.
A named storage location in memory whose value can change while the program runs.
Example: score = 10, then score = 15.
A named value that does not change while the program runs.
Example: PI = 3.14159.
The kind of value that a variable holds, which decides what operations are possible.
Example: Integer, string, float and Boolean.
A data type for whole numbers, with no decimal point.
Example: 7, 0 and -25.
A data type for numbers with a fractional part.
Example: 3.75
A data type for text, a sequence of characters.
Example: "Hello, world"
A symbol that performs an operation on values.
Example: +, -, *, /, == and AND.
Running instructions one after another in order.
Example: Add flour, then add water, then mix.
Choosing between different paths in a program, depending on a condition (using IF statements).
Example: If age is 18 or more, show the login page, otherwise show a message.
Repeating a set of instructions, either a fixed number of times (for loop) or while a condition is true (while loop).
Example: Printing the numbers 1 to 10 with a for loop.
A named block of code that does a particular job and can be used again whenever it is needed.
Example: A function that calculates the area of a circle.
A parameter is the name listed in a function's definition; an argument is the actual value you give when you call it.
Example: In area(5), 5 is the argument.
The result that a function sends back to the part of the program that called it.
Example: area(5) returns 78.5.
When a function calls itself to solve a smaller version of the same problem, until it reaches a simple stopping case.
Example: Finding 5! = 5 x 4!.
A data structure that stores several items of the same type under one name, with each item reached by its position (index).
Example: marks[0] is the first mark in the list.
An ordered collection of items that can usually be changed, and can hold items of different types in some languages.
Example: [10, "Ali", 3.5] in Python.
A data structure that stores values and finds them by keys.
Example: {"name": "Sara", "age": 14}
A piece of code that bundles data (attributes) and actions (methods) together, created from a class.
Example: A "car" object with a colour and a drive() method.
A blueprint or template for creating objects.
Example: A Student class used to create many student objects.
A style of programming that organises code into objects, using ideas such as classes, inheritance, encapsulation and polymorphism.
Example: Java and Python support OOP.
When a new class takes on the attributes and methods of an existing class, and can add its own.
Example: A Dog class inherits from an Animal class.
Keeping an object's data private and allowing access only through its methods.
Example: A bank account balance changed only by deposit() and withdraw().
The ability of different objects to respond to the same method name in their own way.
Example: Both Cat and Dog have speak(), giving "meow" and "woof".
Finding and fixing errors (bugs) in a program.
Example: Using print statements to find why a total is wrong.
An error caused by breaking the rules of the language, which prevents the program from running.
Example: Forgetting a closing bracket.
A mistake in the program's logic that runs without a crash but produces the wrong result.
Example: Using + instead of * to calculate an area.
An error that occurs while the program is running and makes it stop.
Example: Dividing by zero.
Text in the source code that the computer ignores, written to explain the code to humans.
Example: # This line calculates the average.
A software tool that combines a code editor, debugger and other features for writing programs.
Example: Visual Studio Code, IDLE and PyCharm.
A collection of ready-made code that programmers can use in their own programs.
Example: The math library of Python.
A set of rules that lets one program request services or data from another.
Example: A weather app asking a weather service for today's forecast.
A ready-made structure of code that provides a base for building software, so developers do not start from nothing.
Example: Django and React.
A system that records changes to files over time so that earlier versions can be recovered and teams can work together.
Example: Git.
Git is a popular version-control tool. A repository is the folder in which Git stores a project and its history.
Example: Sharing code through a GitHub repository.
A short program, often written in a scripting language, that automates tasks.
Example: A script that renames 100 photos.
The stages of building software: planning, analysis, design, coding, testing, deployment and maintenance.
Example: A school app moving from design to testing to release.
Running a program with different data to check that it works correctly and to find errors.
Example: Entering a negative age into a form to see how the program reacts.
The front end is the part of a website or app that the user sees and uses; the back end is the server-side part that stores data and does the processing.
Example: A shop page (front end) and the order database (back end).
The standard markup language for building the structure and content of web pages.
Example: A heading is written as h1 text.
The language that controls the appearance of web pages, such as colours, fonts and layout.
Example: Making all headings blue.
A programming language that makes web pages interactive and runs in the browser.
Example: A quiz page that shows your score instantly.
A popular high-level, easy-to-read programming language, widely used in education, data science and AI.
Example: print("Hello") shows Hello on the screen.
Designing a website so that its layout adapts to different screen sizes.
Example: A page that rearranges itself on a phone.
Ways of organising data and the standard methods for searching and sorting it.
A way of organising and storing data in a computer so that it can be used efficiently.
Example: Arrays, lists, stacks, queues and trees.
A data structure that works on the Last In, First Out (LIFO) principle: the last item added is the first one removed.
Example: The Undo button, or a pile of plates.
A data structure that works on the First In, First Out (FIFO) principle: the first item added is the first one removed.
Example: Documents waiting in a printer queue.
A collection of items called nodes, in which each node holds a value and a link (pointer) to the next node.
Example: A treasure hunt where each clue points to the next clue.
A data structure with a top node (the root) and branches leading to child nodes, with no loops.
Example: The folder structure on a computer.
A tree in which each node has at most two children.
Example: A binary search tree used to keep data in order.
A data structure of nodes (vertices) joined by connections (edges).
Example: A map of cities and roads, or a social network.
A data structure that stores key-value pairs and uses a hash function to find an item's position quickly.
Example: A phone book that finds a name instantly.
Finding a particular item in a collection of data.
Example: Looking up a student's name in a list.
Checking each item one by one from the start until the target is found or the list ends. The list need not be sorted.
Example: Looking for a card by turning over every card in order.
A fast search method for a sorted list: it repeatedly compares the target with the middle item and discards half of the list each time.
Example: A list of 1 000 000 sorted items needs at most about 20 comparisons.
Arranging data in a particular order, such as smallest to largest or A to Z.
Example: Putting names in alphabetical order.
A simple sorting method that repeatedly compares neighbouring items and swaps them if they are in the wrong order.
Example: Sorting 5, 3, 8, 1 into 1, 3, 5, 8 through repeated swaps.
A fast sorting method that splits the list into halves, sorts each half and then merges the sorted halves together.
Example: Dividing a pile of exam papers, sorting each pile and merging.
A way of describing how the running time or memory of an algorithm grows as the size of the input (n) grows.
Example: Linear search is O(n); binary search is O(log n).
How well an algorithm uses time and memory to solve a problem.
Example: An algorithm that finishes in 1 second is more efficient than one that takes 1 minute.
How organisations store, organise and use large amounts of data.
An organised collection of data stored electronically so that it can be easily searched, updated and managed.
Example: A school's student records.
Software used to create, manage and access a database.
Example: MySQL, PostgreSQL, Oracle and Microsoft Access.
A set of rows and columns in a database that holds data about one type of thing.
Example: A table of students.
One complete set of related data about a single item in a table.
Example: All the details of one student.
A single piece of information stored for each record in a table.
Example: The "Date of birth" column.
A field (or fields) that uniquely identifies each record in a table and is never repeated or empty.
Example: A student ID number.
A field in one table that links to the primary key in another table.
Example: A Class ID in the student table that links to the Class table.
A database that stores data in linked tables and uses keys to connect them.
Example: A school database with separate, linked Student, Teacher and Class tables.
The standard language for asking questions of, and changing data in, a relational database.
Example: SELECT name FROM students WHERE city = 'Lahore';
A request to a database to find, add, change or delete data.
Example: A search for all students who scored over 80.
The four basic database operations: Create, Read, Update and Delete.
Example: Adding a new student, viewing a record, editing a phone number and removing a leaver.
Unnecessary repetition of the same data in several places, which wastes space and can cause inconsistency.
Example: Typing a student's address in ten different tables.
The accuracy, consistency and reliability of data over its whole life.
Example: Making sure a mark cannot be entered as "abc".
Organising a database into well-structured tables to reduce redundancy and improve integrity.
Example: Moving class details into their own table.
A database that does not use the traditional table structure, designed for very large or flexible data.
Example: MongoDB storing documents.
Extremely large and fast-growing sets of data that are too big for ordinary tools. They are often described by the three Vs: volume, velocity and variety.
Example: Millions of posts uploaded to social media every day.
A large central store of data collected from many sources and used for reporting and analysis.
Example: A company storing years of sales data for analysis.
Searching large sets of data for hidden patterns and useful knowledge.
Example: A shop discovering that people who buy tea often buy biscuits.
The field that uses statistics, programming and domain knowledge to collect, analyse and understand data.
Example: Predicting next month's sales.
Threats, protections and the rules of using computers responsibly.
The protection of computers, networks, programs and data from attack, damage or unauthorised access.
Example: Using strong passwords, updates and antivirus software.
Short for "malicious software": any software designed to harm a computer or steal data.
Example: Viruses, worms, trojans, ransomware and spyware.
A malicious program that attaches itself to a file or program, spreads when that file is run and may damage data.
Example: An infected file received by email.
A malicious program that spreads by itself across networks, without needing a host file.
Example: A worm that copies itself to every computer on a network.
Malware that pretends to be useful software but carries out harmful actions once installed.
Example: A "free game" that secretly steals passwords.
Malware that locks or encrypts a victim's files and demands payment to unlock them.
Example: A hospital's files being locked until a payment is made.
Malware that secretly gathers information about a user and sends it to someone else.
Example: A program that records the sites you visit.
Software that shows unwanted advertisements, sometimes tracking what you view.
Example: Pop-ups that appear after installing a free tool.
A program or device that secretly records the keys you press, to steal passwords and other data.
Example: Software that captures a typed bank password.
A network of infected computers controlled remotely by an attacker, often used to send spam or launch attacks.
Example: Thousands of hijacked devices attacking one website.
A fraud attempt that uses fake emails, messages or websites to trick people into giving personal information such as passwords or bank details.
Example: An email "from the bank" asking you to click a link and log in.
Tricking people, rather than machines, into giving up confidential information or access.
Example: A caller pretending to be technical support to learn your password.
A person who uses computer skills to gain access to systems. A white-hat (ethical) hacker has permission and aims to improve security; a black-hat hacker acts illegally.
Example: A security expert hired to test a company's network.
Trying every possible password or key until the right one is found.
Example: A program testing thousands of passwords per second.
A denial-of-service attack floods a server with so much traffic that real users cannot use it. DDoS uses many computers at once (distributed).
Example: A website crashing during a coordinated flood of requests.
An attack that inserts harmful database commands into a website input field to read or damage data.
Example: Typing a malicious command into a login box.
An attack in which someone secretly intercepts and may change the communication between two parties.
Example: An attacker on public Wi-Fi reading unencrypted messages.
A security flaw that is unknown to the software maker, so no patch exists yet.
Example: An attack that uses a hidden flaw before the company has fixed it.
Scrambling data using an algorithm and a key so that only authorised people can read it.
Example: HTTPS and WhatsApp messages are encrypted.
Turning encrypted data back into readable form using the correct key.
Example: Unlocking a protected file with a password.
Plaintext is readable data; ciphertext is the scrambled, unreadable result of encryption.
Example: "HELLO" becoming "KHOOR" with a simple Caesar cipher (shift of 3).
Encryption that uses the same secret key to encrypt and to decrypt.
Example: A password-protected ZIP file.
Encryption that uses a pair of keys: a public key that can be shared, and a private key kept secret.
Example: Used to set up secure HTTPS connections.
A one-way process that turns data into a fixed-length code. It cannot be reversed, so it is used to check data and store passwords safely.
Example: A website storing a hash of your password instead of the password itself.
An electronic code, created with a private key, that proves who sent a document and that it has not been altered.
Example: A signed software update.
A digital certificate that proves a website's identity and enables an encrypted (HTTPS) connection. TLS is the modern successor to SSL.
Example: The padlock beside a web address.
Proving who you are before gaining access.
Example: Entering a username and password.
A login that needs two different kinds of proof, such as a password plus a code sent to your phone. Multi-factor authentication (MFA) can use more than two.
Example: Entering a password and then an SMS code.
Identification using unique body features.
Example: Fingerprint, face and iris recognition.
A program that stores strong, unique passwords securely so that you need to remember only one master password.
Example: Using a password manager to create a different password for each site.
A long password that is hard to guess, mixing letters, digits and symbols, and not reused across accounts.
Example: A passphrase of four unrelated words plus a number.
A program that scans for, detects and removes malware.
Example: Windows Defender.
An incident in which private or protected data is accessed or stolen without permission.
Example: Millions of customer emails leaked from a company's database.
Using another person's personal information without permission, usually to commit fraud.
Example: Opening a loan in someone else's name.
Crime carried out using computers or networks, such as fraud, hacking, harassment and illegal access to data. Many countries have specific laws; in Pakistan, the Prevention of Electronic Crimes Act (PECA) 2016 is one of them.
Example: Online banking fraud.
Using digital devices or platforms to harass, threaten or embarrass another person.
Example: Sending hurtful messages in a group chat.
The trail of data you leave online, from posts and searches to photos and location.
Example: Your social media posts remain visible after you delete them from your phone.
The right to control who can see and use your personal information.
Example: Choosing "friends only" on a profile.
The legal right of a creator to control how their original work is copied, shared and used.
Example: Using someone else's photograph without permission.
Presenting another person's work or ideas as your own without crediting them.
Example: Copying a paragraph from a website into an essay.
A set of licences that allow creators to share their work with clear conditions for reuse.
Example: A photograph marked "CC BY" that you may reuse if you credit the creator.
The illegal copying or use of software without a licence.
Example: Using a cracked copy of a paid program.
The European Union's law (in force from 2018) on how personal data must be collected, stored and used, giving people rights over their data.
Example: A website asking permission before saving cookies.
Behaving responsibly, respectfully and safely when using technology and the Internet.
Example: Checking facts before sharing a post.
The accepted rules of polite behaviour online.
Example: Not typing in capital letters, which looks like shouting.
Misinformation is false information shared without intent to deceive; disinformation is false information spread deliberately.
Example: A fake news story shared in a chat group.
A fake video, image or audio created with AI to make a person appear to say or do something they never did.
Example: A fake video of a public figure.
The ideas behind smart machines and the newest areas of computing.
The ability of a computer system to perform tasks that normally need human intelligence, such as learning, recognising speech or images, and making decisions.
Example: A voice assistant that answers questions.
A branch of AI in which computers learn patterns from data and improve at a task without being given exact step-by-step rules.
Example: A spam filter that learns from millions of emails.
A kind of machine learning that uses neural networks with many layers to learn from large amounts of data.
Example: Image recognition and speech recognition.
A computing model inspired by the brain, made of layers of connected nodes ("neurons") that process data and learn by adjusting the strength of their connections.
Example: A network that learns to recognise handwritten digits.
The examples used to teach a machine-learning model.
Example: Thousands of labelled photos of cats and dogs.
The result of training: a mathematical system that takes an input and gives a prediction or output.
Example: A model that predicts house prices.
Machine learning from labelled examples, where the correct answers are provided during training.
Example: Learning to identify spam from emails marked "spam" and "not spam".
Machine learning that finds patterns in data that has no labels.
Example: Grouping customers with similar buying habits.
Machine learning in which a system learns by trial and error, receiving rewards or penalties for its actions.
Example: A program learning to play a game by winning and losing.
When a model learns the training data too closely, including its noise, so it performs poorly on new data.
Example: A model that scores 100% on practice questions but fails the real test.
Unfair results from an AI system, often because its training data was unbalanced or reflected human prejudice.
Example: A hiring tool that favours one group because of biased past data.
The branch of AI that lets computers understand, interpret and produce human language.
Example: Translation apps and chatbots.
The branch of AI that lets computers understand images and video.
Example: Face unlock on a phone.
Technology that converts spoken words into text or commands.
Example: Dictating a message to a phone.
A program that holds a conversation with people in text or speech.
Example: A customer-support assistant on a website.
An AI model trained on huge amounts of text that can predict and generate language, answer questions and write.
Example: The model behind AI chat assistants.
AI that creates new content, such as text, images, audio, video or code, based on patterns learned from data.
Example: Creating a picture from a written description.
The instruction, question or text you give to an AI system.
Example: "Explain photosynthesis in simple words."
Writing clear, well-structured prompts to get better results from an AI system.
Example: Giving the topic, the audience and the format in a prompt.
When an AI system produces information that sounds convincing but is false or invented.
Example: An AI quoting a book that does not exist.
A small piece of text (a word or part of a word) that a language model reads and writes.
Example: The word "unhappy" may be split into "un" and "happy".
A hypothetical AI that could learn and do any intellectual task a human can. It does not exist today.
Example: A machine equally good at maths, art and conversation.
A test proposed by Alan Turing in 1950: if a person cannot tell whether they are talking to a machine or a human, the machine is said to show intelligent behaviour.
Example: A judge chatting with two unseen partners.
The study of how to build and use AI fairly, safely, transparently and responsibly.
Example: Checking an AI system for bias before using it.
An AI system that suggests items a user is likely to want, based on their past behaviour and that of similar users.
Example: A video site suggesting what to watch next.
Using technology to perform tasks with little or no human effort.
Example: A factory conveyor belt that sorts parcels automatically.
The design, building and use of robots, machines that can sense, decide and act.
Example: A robot arm assembling cars.
A vehicle that can drive itself using sensors and AI.
Example: A self-driving car.
A network of everyday physical objects with sensors and software that connect to the Internet and share data.
Example: A smart thermostat controlled from a phone.
Using remote servers on the Internet to store data, run programs and provide services, instead of using only your own computer.
Example: Editing a document online and saving it in the cloud.
Three cloud service models. SaaS (Software as a Service) gives finished software; PaaS (Platform as a Service) gives a platform to build apps on; IaaS (Infrastructure as a Service) gives virtual servers and storage.
Example: Using web email is SaaS.
Processing data close to where it is created (on or near the device) instead of sending it all to a distant data centre.
Example: A smart camera that detects motion by itself.
A shared digital ledger that records transactions in linked blocks. Once recorded, entries are very hard to change.
Example: The record of Bitcoin transactions.
Digital money that uses cryptography and a blockchain to secure transactions, without a central bank. Bitcoin, created in 2009 by a person or group using the name Satoshi Nakamoto, was the first.
Example: Bitcoin and Ethereum.
Computing that uses quantum bits (qubits), which can be in a combination of 0 and 1 at once, to solve certain problems much faster than ordinary computers.
Example: Research into simulating new materials.
Technology that overlays digital objects on a view of the real world.
Example: A phone app that shows furniture in your room.
Technology that places the user in a completely computer-generated 3D environment, usually through a headset.
Example: Exploring an ancient city in a headset.
Making a solid object by adding material layer by layer, following a digital design.
Example: Printing a plastic spare part.
A virtual copy of a real object, process or system, used to test and monitor it.
Example: A virtual model of a wind turbine.
The everyday skills and words of using computers at school, work and home.
All the technology used to collect, store, process, share and communicate information.
Example: Computers, phones, the Internet and email.
The ability to find, evaluate, create and communicate information safely and effectively using digital tools.
Example: Checking whether a website is trustworthy before using it.
Software for writing, editing, formatting and printing text documents.
Example: Microsoft Word and Google Docs.
Software that organises data in rows and columns of cells and performs calculations with formulas.
Example: Microsoft Excel and Google Sheets.
A cell is one box in a spreadsheet where a row and column meet. A cell reference is its address, made from the column letter and row number.
Example: B3 is the cell in column B, row 3.
An instruction in a spreadsheet cell that calculates a value, usually starting with an equals sign.
Example: =A1+B1 adds the values in A1 and B1.
A built-in formula that carries out a common calculation.
Example: =SUM(A1:A10) adds ten cells; =AVERAGE(B1:B5) finds their mean.
A picture that shows data, such as a bar chart, line graph or pie chart.
Example: A bar chart of exam marks.
Software for making slides that combine text, pictures, audio and video.
Example: PowerPoint and Google Slides.
A ready-made design or layout that you can reuse and fill in.
Example: A certificate template.
A feature that combines one document with a list of names and details to make many personalised copies.
Example: Sending the same letter with a different name on each.
Copy duplicates selected content; cut removes it; paste puts the copied or cut content in a new place. Shortcuts: Ctrl+C, Ctrl+X and Ctrl+V.
Example: Copying a table from a web page into a document.
A temporary storage area where copied or cut content is held until it is pasted.
Example: The place where the last copied sentence waits.
A key combination that performs a command faster than using the menu.
Example: Ctrl+Z to undo, Ctrl+S to save.
The main screen of an operating system, where icons, files and folders are shown.
Example: The screen you see after you log in.
A small picture that represents a program, file or action.
Example: The trash-can icon for deleted items.
A bar, usually at the bottom of the screen, that shows open programs and gives quick access to apps and settings.
Example: Switching between a browser and a document.
A rectangular area on the screen that displays a program or a document.
Example: A browser window.
The marker on the screen that shows where typing or pointing will take place.
Example: The blinking line in a text box.
The style, size and shape of the letters in text.
Example: Times New Roman 12 pt.
An email address identifies a mailbox (user@domain). An attachment is a file sent together with an email message.
Example: Sending a CV as an attachment.
CC (carbon copy) sends a copy of the message to other people who can be seen by everyone. BCC (blind carbon copy) hides those recipients from each other.
Example: Using BCC to email a large class without showing everyone's address.
Unwanted, unsolicited messages, usually advertising or scams, sent in bulk.
Example: Junk email offering a prize.
Websites and apps where people create and share content and talk to each other.
Example: Facebook, Instagram, YouTube and X.
A website or page of regularly updated articles, usually in reverse date order.
Example: A teacher's weekly class blog.
A website that many people can edit together.
Example: Wikipedia.
Buying and selling goods and services over the Internet.
Example: Ordering a book online.
Managing a bank account through a website or app.
Example: Checking a balance on a phone.
Learning through digital tools and the Internet.
Example: Taking a lesson on an educational website.
Meeting by live video and audio over the Internet.
Example: A virtual class on a video-call app.
A tab lets you keep several pages open in one browser window. A bookmark saves a page's address. History lists the pages you visited.
Example: Bookmarking a useful revision page.
Files such as images and scripts that a browser saves so that pages load faster the next time.
Example: A site opening faster on your second visit.
A small window that suddenly appears over the page you are viewing, often an advertisement.
Example: A window offering a prize. Close it without clicking inside it.
The gap between people who have access to modern technology and the Internet, and people who do not.
Example: Students without Internet at home.
Discarded electronic devices such as old phones and computers. It contains useful materials but also harmful substances if thrown away badly.
Example: Recycling an old laptop at a collection point.
Using computers and other technology in ways that reduce energy use and environmental harm.
Example: Switching devices off when not in use.
Designing equipment and work habits to fit the human body and prevent strain and injury.
Example: Sitting with your back supported and your screen at eye level.
Key people, inventions and kinds of machine in the story of computing.
An ancient counting tool with beads on rods, used to do arithmetic.
Example: Still taught in some schools to learn place value.
The English mathematician who designed the Difference Engine and the Analytical Engine in the 1800s. The Analytical Engine had features of a modern computer, so he is often called the "father of the computer".
Example: The Analytical Engine was designed but never fully built in his lifetime.
The English mathematician who, in 1843, published what is regarded as the first algorithm meant to be run on a machine, for Babbage's Analytical Engine.
Example: She is often called the first computer programmer.
The British mathematician who described the theoretical Turing machine (1936), helped break German codes in the Second World War and proposed the Turing test.
Example: A founder of computer science and AI.
One of the first large electronic general-purpose computers, completed in the United States in 1945 and shown to the public in 1946. It used thousands of vacuum tubes.
Example: It filled a large room and weighed about 30 tonnes.
A glass electronic component used as a switch or amplifier in early computers. It was large, hot and unreliable.
Example: The main component of first-generation computers.
A tiny semiconductor switch invented in 1947 at Bell Laboratories. It replaced vacuum tubes and made computers smaller, cheaper and more reliable.
Example: Modern processors contain billions of transistors.
A tiny chip containing many electronic components. The first working integrated circuits were made in 1958 and 1959.
Example: A processor chip.
An entire CPU on a single chip. The first commercial one was the Intel 4004, released in 1971.
Example: The processor in a laptop.
Five stages of computing: 1st (vacuum tubes), 2nd (transistors), 3rd (integrated circuits), 4th (microprocessors) and 5th (often described as AI and parallel computing).
Example: Moving from room-sized machines to pocket-sized phones.
The observation, made by Gordon Moore in 1965 and later refined, that the number of transistors on a chip roughly doubles about every two years.
Example: One reason computers have become so powerful.
A computer design in which instructions and data are stored together in the same memory, and the CPU fetches and executes instructions one after another (the stored-program concept).
Example: Used as the basis of almost all modern computers.
An early computer network funded by the US government, first connected in 1969. It was the forerunner of the Internet.
Example: The first message was sent between UCLA and the Stanford Research Institute.
The British scientist who invented the World Wide Web in 1989-1991 while working at CERN.
Example: He created the first web browser and web server.
A computer designed for use by one person at a time.
Example: A desktop or laptop computer.
A portable personal computer with a built-in screen, keyboard and battery.
Example: A student's notebook computer.
A flat, touchscreen computer, usually larger than a phone and without a physical keyboard.
Example: An iPad.
A mobile phone that works as a small computer, with a touchscreen, apps and Internet access.
Example: A phone used to browse, take photographs and make calls.
A small computer device worn on the body.
Example: A smartwatch.
A very large, powerful computer used by big organisations to process huge amounts of data reliably.
Example: A bank's central system.
An extremely powerful computer, made from many processors, used for very complex calculations.
Example: Forecasting the weather or simulating a new medicine.
Analogue signals vary continuously (like a vinyl record's groove); digital signals use separate values, usually 0 and 1.
Example: A digital clock shows numbers; an analogue clock has moving hands.
Many exam mistakes come from mixing up two similar words. This table puts the differences side by side.
| Terms | The difference |
|---|---|
| Hardware vs software | Hardware is the physical equipment you can touch; software is the set of programs that run on it. |
| RAM vs ROM | RAM is temporary working memory that is erased when power is off; ROM is permanent memory that keeps start-up instructions. |
| Memory vs storage | Memory (RAM) holds what is being used now and is fast and temporary; storage (SSD, HDD) keeps files for the long term. |
| Data vs information | Data is raw facts; information is data that has been processed so that it has meaning. |
| Bit vs byte | A bit is a single 0 or 1; a byte is 8 bits. |
| Mbps vs MBps | Mbps is megabits per second (line speed); MBps is megabytes per second (file speed). Divide Mbps by 8 to get MBps. |
| Internet vs World Wide Web | The Internet is the global network of connected computers; the web is one service (linked pages) that runs on it. Email also uses the Internet but is not part of the web. |
| LAN vs WAN | A LAN covers a small area such as a school; a WAN covers a large area, and the Internet is the biggest WAN. |
| Hub vs switch | A hub sends data to every device; a switch sends data only to the device that needs it. |
| HTTP vs HTTPS | HTTPS is HTTP with encryption, so that data between the browser and the site is protected. |
| Compiler vs interpreter | A compiler translates the whole program first and then it runs; an interpreter translates and runs one line at a time. |
| Syntax error vs logic error | A syntax error breaks the language rules, so the program will not run; a logic error runs but gives the wrong answer. |
| Virus vs malware | Malware is the general name for all harmful software; a virus is one kind of malware that attaches to files and spreads when they are run. |
| Encryption vs hashing | Encryption can be reversed with the right key; hashing is one-way and cannot be reversed. |
| Authentication vs authorisation | Authentication proves who you are (login); authorisation decides what you are allowed to do once logged in. |
| Cache vs cookie | A cache stores copies of content to load pages faster; a cookie stores small pieces of information about you or your visit. |
| AI vs machine learning vs deep learning | AI is the broad goal of smart machines; machine learning is a way of achieving AI by learning from data; deep learning is a type of machine learning that uses many-layered neural networks. |
| Virtual reality vs augmented reality | VR replaces your view with a virtual world; AR adds digital objects to your view of the real world. |
Some terms are best understood by calculation. These examples show how data representation, storage and networks work in practice.
Convert the binary number 110101 to decimal.
Write the place values from the right: 1, 2, 4, 8, 16, 32. The binary digits 1 1 0 1 0 1 sit under 32, 16, 8, 4, 2, 1.
Add the places that have a 1: 32 + 16 + 4 + 1 = 53.
Convert 45 to binary by repeated division by 2.
45 ÷ 2 = 22 remainder 1; 22 ÷ 2 = 11 r 0; 11 ÷ 2 = 5 r 1; 5 ÷ 2 = 2 r 1; 2 ÷ 2 = 1 r 0; 1 ÷ 2 = 0 r 1.
Read the remainders from the bottom up: 101101. Check: 32 + 8 + 4 + 1 = 45 ✓.
Convert 10101111 to hexadecimal and decimal.
Split into groups of 4 bits: 1010 and 1111. 1010 = 10 = A; 1111 = 15 = F. So the answer is AF in hexadecimal.
In decimal: A × 16 + F = 10 × 16 + 15 = 175.
How much storage does an uncompressed Full HD image (1920 × 1080 pixels) need if each pixel uses 24 bits (3 bytes)?
Number of pixels = 1920 × 1080 = 2 073 600.
Size = 2 073 600 × 3 bytes = 6 220 800 bytes ≈ 6.2 MB. Compression such as JPEG can reduce this greatly.
How long does it take to download a 150 MB file on a 24 Mbps connection (ignoring delays)?
Convert to bits: 150 MB × 8 = 1200 megabits.
Time = 1200 ÷ 24 = 50 seconds.
How many 4 MB photos fit on a 32 GB memory card? (Use 1 GB = 1000 MB.)
32 GB = 32 000 MB. Photos = 32 000 ÷ 4 = 8000 photos. In practice the card holds a little less, because of formatting and file overhead.
A circuit gives the output Q = A AND (NOT B). Complete its truth table.
| A | B | NOT B | Q = A AND (NOT B) |
|---|---|---|---|
| 0 | 0 | 1 | 0 |
| 0 | 1 | 0 | 0 |
| 1 | 0 | 1 | 1 |
| 1 | 1 | 0 | 0 |
Q is 1 only when A is 1 and B is 0.
Try each question before opening the answer.
Input, processing, output and storage.
Because its contents are lost when the power is switched off.
8 + 0 + 0 + 1 = 9.
The Internet is the worldwide network of connected networks; the World Wide Web is a service of linked web pages that runs on the Internet.
A logic error: the program runs, but gives an incorrect result.
60 × 8 = 480 megabits; 480 ÷ 8 = 60 seconds.
Phishing tricks a person into revealing information, usually through a fake message or website; a virus is a malicious program that attaches to files and spreads.
It uniquely identifies each record in the table, so no two records have the same key.
This guide works well as a class reference. Ask students to choose five terms they find difficult, write the definition in their own words, and add an original example. Use the confused-pairs table for quick starters ("What is the difference between a hub and a switch?"). Practical activities: have pupils sort real objects into input and output devices; convert their birth year or age into binary; calculate the time to download a file at different speeds; and design a simple password-safety poster. Always supervise Internet use and discuss online safety. Definitions are simplified for learning; please check that they match the wording of the syllabus used by your examination board.
This article is original EDUSAMBAM writing. Definitions were checked against the authoritative sources below and simplified for learners. Diagrams are original.
Review note: technology changes quickly and some definitions are simplified for beginners. A teacher should check them against the syllabus used by your readers, and check the product names and examples from time to time.
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