HTML/CSS/JS, protocols, internet · CPU, memory, binary, logic · 94 terms
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How the internet works, web technologies, and protocols.
5HyperText Markup Language: the markup language used to structure content on webpages.
The skeleton of a webpage. HTML provides the bones and structure — headings, paragraphs, images, links. CSS adds skin and styling on top.
Cascading Style Sheets: a language used to style and lay out webpages, including colours, fonts, spacing and positioning.
If HTML is the skeleton, CSS is the clothing and appearance — it makes things look good without changing the underlying structure.
A programming language used to add interactivity to webpages.
HTML = skeleton, CSS = appearance, JavaScript = the muscles that make it move and react. Click a button, see a drop-down, fill a form that validates in real-time — all JavaScript.
A single HTML document that can be displayed in a web browser.
A collection of linked webpages and resources. Your coursework report must be accessible from index.html.
A markup instruction written in angle brackets, such as <p> or <h1>.
A complete part of a webpage, usually made of an opening tag, content and a closing tag. Example: <p>Hello</p>
Extra information inside an opening tag, such as href in an <a> tag or src in an <img> tag.
A clickable link that takes the user to another page, file, section or resource. Uses the <a> tag and href attribute.
A webpage section used to collect user input.
An action such as a click, keypress or form submission that code can respond to.
JavaScript code that waits for a particular event and runs a function when it occurs.
Like a doorbell. The listener waits patiently. When someone presses the button (event), it runs the code (rings the bell).
A browser's structured representation of a webpage that JavaScript can read and change.
Designing a webpage/interface so it works well on different screen sizes/devices.
Software used to request, interpret and display webpages. Examples: Chrome, Edge, Firefox.
A computer/program that stores web resources and sends them to clients in response to requests.
A model where a client requests a service/resource and a server processes the request and sends back a response.
A restaurant: you (client) order food; the kitchen (server) prepares it and sends it back. The waiter is the network. 2022 exam used browser/server directly.
A message sent by a client asking a server for a resource or service.
The server's reply to a client request, such as an HTML page or data.
Uniform Resource Locator: the address used to locate a resource on the web.
An agreed set of rules for communication between devices/systems. Examples: HTTP, HTTPS, TCP, IP.
Like a language — both sides need to agree on the same rules to communicate. If one device speaks HTTP and the other speaks a different protocol, they can't understand each other.
HyperText Transfer Protocol: protocol used for transferring web pages/resources between browser and server. Unsecured.
Secure version of HTTP that uses encryption/TLS to protect data in transit.
The padlock in your browser = HTTPS. Know the difference from HTTP and why it matters (encryption).
Transmission Control Protocol: breaks data into packets, numbers them, checks delivery and reassembles them in order.
Sending a long letter by tearing it into numbered pages and posting them separately. TCP ensures all pages arrive and puts them back in order.
Internet Protocol: responsible for addressing and routing packets across networks.
Voice over Internet Protocol: using IP networks to carry voice/video communication, such as Zoom or WhatsApp calls.
A small chunk of data sent across a network with addressing/control information.
Sending data as separate packets that may travel different routes and are reassembled at the destination.
A numerical address used to identify a device/network interface on an IP network.
Domain Name System: translates human-readable domain names (like google.com) into IP addresses.
The phonebook of the internet. You know a name (google.com), DNS finds the number (IP address) for you.
Transforming data into unreadable form using a key so it cannot be understood without decryption.
Scrambling the letters in a message using a secret code. Only someone with the key can unscramble it.
Converting encrypted data back into readable form using the correct key.
CPU internals, memory, storage, operating systems and data representation.
6A combination of hardware, software, data, communications and users working together.
The physical parts of a computer system, such as CPU, RAM, keyboard, screen or storage.
Programs and data/instructions that run on computer hardware.
Software that manages computer hardware and provides a platform for application software, such as an operating system.
Software designed to help users perform specific tasks, such as word processing, browsing or editing images.
System software that controls hardware resources and provides services/interface for users and applications.
The OS is the manager of a building. It controls who uses which rooms (memory management), schedules meetings (processor scheduling), and provides services to the people inside (applications).
How the OS controls and coordinates hardware resources such as CPU time, memory, storage and input/output devices.
Directly asked in 2025 — know the four main OS functions: file management, memory management, resource management, and processor scheduling.
How the OS organises, stores, tracks and controls access to files on storage devices.
How the OS allocates RAM to programs and manages movement of data between memory and storage.
How the OS decides which process uses the CPU and when.
Software stored in hardware, often in ROM/flash, that controls low-level device operation. Example: BIOS/UEFI.
Firmware used during computer start-up to initialise hardware and load the operating system.
The main processor that fetches, decodes and executes instructions. Contains the ALU, CU, registers and cache.
The brain of the computer. Just as your brain processes information, makes decisions, and coordinates your body, the CPU processes instructions and coordinates all other components.
CPU component that performs arithmetic (add, subtract, multiply) and logical operations (AND, OR, NOT, comparisons).
CPU component that directs and coordinates operations, including fetching, decoding and executing instructions.
The conductor of an orchestra. The CU doesn't play any instruments itself — it coordinates all the other parts (ALU, registers, memory) to work together in the right order.
A very small, very fast storage location inside the CPU used to hold data, instructions or addresses temporarily.
The scratchpad on a chef's counter — tiny, right there at hand, used for the current calculation. Much faster than going to the fridge (RAM) or pantry (storage).
A register that stores the memory address of the next instruction to be executed.
A CPU register used to store intermediate results/data being operated on by the ALU.
Fast, small memory close to or inside the CPU used to store frequently needed data/instructions.
A chef keeps their most-used spices on the counter (cache) rather than fetching them from the cupboard (RAM) every time. Faster access = faster cooking/processing.
The number of CPU clock pulses per second, usually measured in hertz (Hz). Higher speed can mean more cycles per second.
Like the tempo of a metronome — a faster beat means the CPU can do more "ticks" of work per second.
A processing unit within a CPU capable of executing instructions. Multiple cores can process more work in parallel.
A quad-core CPU is like having 4 chefs in one kitchen — they can cook 4 different dishes simultaneously instead of one at a time.
The repeated process by which the CPU: (1) Fetches an instruction from memory, (2) Decodes it to find out what to do, (3) Executes it.
Fetch → Decode → Execute. Like: Find the recipe, Decide what it says, Do it.
Volatile primary memory used to store programs/data while the computer is running. Contents lost when power is off.
Your desk surface while you work. You spread papers (open programs) across it. When you finish work and clear the desk, everything is gone — nothing is permanently stored.
Non-volatile memory used to store permanent/start-up instructions such as firmware. Cannot be easily changed.
Memory whose contents are lost when power is switched off, such as RAM and registers.
Memory/storage that keeps data when power is off, such as ROM, SSDs and hard drives.
Memory directly accessible by the CPU, mainly RAM, ROM and cache/registers.
Long-term non-volatile storage for files and programs, such as HDDs, SSDs and USB drives.
Magnetic secondary storage with spinning platters and moving parts. Generally cheaper per GB, but slower than SSD.
Electronic secondary storage with no moving parts, usually faster, more durable and lighter than HDD.
Common comparison question: HDD vs SSD — HDD cheaper/larger capacity, SSD faster/more durable/no moving parts.
A memory-management technique where storage (HDD/SSD) is used as extra temporary memory when RAM is full.
When your desk is full, you put some papers in a drawer (storage). You can still access them but it takes longer to get them. Virtual memory is slower because storage is slower than RAM.
A communication pathway that carries data, addresses or control signals between computer components.
The main circuit board that connects CPU, memory, storage and other components.
The smallest unit of data, representing a binary value 0 or 1.
A group of 8 bits. Used in storage and character encoding contexts.
Base-2 number system using only digits 0 and 1. Computers represent all data in binary.
Like a light switch — only two states. Computers are built from billions of transistors each in state 0 or 1. From these two states, everything — numbers, text, images, video — can be encoded.
Base-10 number system using digits 0-9. The normal human number system.
Base-16 number system using digits 0-9 and letters A-F. Often used as a compact representation of binary.
A shorthand for binary — every 4 binary bits become one hex digit. So 1111 = F, making long binary numbers much easier to read. Used for colours (#FF6B6B), memory addresses, and more.
2025 exam asked about #0A33F0 style hex colour conversion. Know how to convert hex pairs to RGB values (0–255).
A character encoding standard that represents common characters using numeric codes. Standard ASCII uses 7 bits (128 characters).
Like a secret code where A=65, B=66 etc. The computer stores numbers; when displaying text it looks up what character each number represents.
A character encoding standard designed to represent characters from many languages and symbols, including emojis.
Unicode is more globally compatible than ASCII — ASCII can't represent Irish fada characters, Chinese characters, or emojis. Unicode can.
A system for representing characters as numbers/binary so computers can store and transmit text. ASCII and Unicode are examples.
A way of representing colour using red, green and blue component values, often 0–255 each or as hexadecimal pairs.
The smallest addressable picture element in a digital image.
The number/detail of pixels in an image or display, often expressed as width × height or pixels per inch (PPI).
Reducing the number of bits needed to store/transmit data.
Compression where original data can be perfectly reconstructed. Useful for text/code/data files.
Compression where some data/detail is permanently removed to reduce file size. Common for images/audio/video (e.g. JPEG, MP3).
Lossless = zipping a file — compress and restore perfectly. Lossy = making a photocopy — you lose some quality but the file is much smaller.
Low-level binary instructions that can be executed directly by a processor.
A low-level programming language using mnemonics closely related to machine instructions.
A programming language closer to human language and independent of a specific CPU architecture, such as Python or JavaScript.
A programming language close to machine code and tied to processor architecture, such as assembly.
The observation that the number of transistors on integrated circuits roughly doubles over time, historically about every two years.
Know the limitation: we are approaching physical limits to how small transistors can be made (near atomic scale).
An early electronic component used before transistors; bulky, hot and less reliable.
A CPU implemented on a single integrated circuit/chip. Key milestone in computing history.
Early packet-switching network considered a forerunner of the Internet. Developed in the late 1960s.
A general-purpose computer affordable and practical for individual users. The PC revolution in the 1970s–80s changed computing from a specialist tool to an everyday device.
Using remote servers over the internet for storage, software or computing resources instead of relying only on local machines.
Instead of keeping all your files on your laptop, you store them in Google Drive — they live on someone else's server somewhere in the world. You access them over the internet.
Processing data close to where it is generated instead of sending everything to central cloud servers.
Key advantage: reduced latency (less delay) because data doesn't have to travel far.
A network of everyday physical devices with sensors/software/network connectivity that collect and exchange data.
Your smart home: fridge, thermostat, doorbell, and kettle all connected to the internet and each other. The "things" (not just computers) are all on the network.
Computing approach using quantum phenomena; may solve certain problems dramatically faster than classical computers, but is expensive and complex.
A decentralised, tamper-resistant ledger where records are linked using cryptographic methods.
A public notebook shared by thousands of people simultaneously. When a new transaction is added, everyone's copy updates. Changing one entry would be spotted immediately because it wouldn't match everyone else's copy.
Verifying identity using biological characteristics such as fingerprint, face or iris.
Discuss: convenience (+), hard to steal (+), privacy concerns (−), spoofing risk (−).