The third generation of mobile phone telecommunications network that enables mobile devices to connect to the internet.


The fourth generation of mobile phone telecommunications network that enables mobile devices to connect to the internet.



Advanced audio coding - a standard lossy compression audio format.


Audio interchange file format - an uncompressed audio file format developed by Apple.


A sequence of logical instructions for carrying out a task. In computing, algorithms are needed to design computer programs.


Arithmetic logic unit - a component of the CPU that performs calculating functions such as addition and subtraction.


Advanced Micro Devices, Inc. is an American multinational semiconductor company based in Sunnyvale, California, United States, that develops computer processors and related technologies for business and consumer markets


The maximum height of a wave from the middle of the wave to its crest or trough.


A Google-produced operating system based on Linux.


A software program that allows a user to perform a specific task.

ARM architecture

ARM, originally Acorn RISC Machine, later Advanced RISC Machine, is a family of reduced instruction set computing architectures for computer processors, configured for various environments.
ASCII American Standard Code for Information Interchange. A 7-bit character set used for representing English keyboard characters.
assignment Setting the value of a variable in a computer program.
audio sample A digital representation of a sound.
augmented reality Where the real world and technology are combined in a live state.


backup A copy of important files that is kept separately in case the original files are lost or damaged.


Benchmarking is a test used to assess the performance of a computer. Different types of benchmark software are used for the different kinds of application you might want a computer to do.


Basic input output system - the basic firmware that is embedded in the computer ROM chip used to start a computer.


A number system that contains two digits, 0 and 1. Also known as base 2.


The smallest unit of data in computing represented by a 1 in binary.
bit depth The number of bits available to store an audio sample.
bit rate In computing, the number of bits processed per second.


A data type in computing which only has two possible values, true or false.


the program which takes the computer through steps that lead up to the loading of the operating system (OS). It happens between turning on the power and the computer beeping to say it is starting to load the OS.


An application used to view web pages, eg Internet Explorer or Google Chrome.


A temporary area of computer memory used to store data for running processes.
bug An error in a program that causes it to fail.


The wires through which data travels from one part of a computer to another on the motherboard.



A piece of temporary memory. It can refer to a part of the RAM, storage disk, CPU, or an area for storing web pages.


Circuit component which stores and discharges electrical current. They are made from two parallel metal plates separated by an insulator (called a dielectric).
chip An electronic circuit that computer systems are made from.


Complex instruction set computing - a type of CPU found in desktop and laptop computers.
class In computing, a class is a category of objects in object orientated programming.

clock speed

The speed of a computer CPU, measued in hertz
cloud A term often used to describe a location on the internet from which software applications are run and where data is stored.

cloud computing

Cloud computing is a variant of utility computing, where managed pool(s) of computing resources are made available on a convenient on-demand basis. It has minimal overheads, due to reduced management requirement and service provider interaction. A key characteristic is elasticity within the provisioning process, allowing rapid deployment and scaling back of the resource usage.
codec A program that encodes or decodes digital information. They are used to create or read audio and video files.
Colossus The first programmable electronic computer, used in Britain during World War 2.

command line

A method of running programs and working on a computer using only text. This contrasts with a graphical interface which uses clickable icons and menus.
compression A method of reducing file sizes, particularly in digital media such as photos, audio and video.
constant A value in computer programming that does not change.

control unit

The component of the CPU that manages instructions.


A set of rights that prevents people copying and distributing a piece of work without the copyright holder's permission.


A processing unit within a CPU. CPUs can have multiple cores.


A computer file that is damaged, possibly unusable.


Central processing unit - the brain of the computer that processes program instructions. Also called a microprocessor.

Cyber security

Cybersecurity can be defined as the protection of systems, networks and data in cyber space. It is a critical issue for all businesses.
CPU Central processing unit - the brain of the computer that processes program instructions. Also called a microprocessor.
Creative Commons (CC) licence One of several copyright licences that allows free sharing and distribution of a product.
CSS Cascading Style Sheet - used to format the style of a web page.
cyberterrorism Illegal terrorist activity carried out online.



Units of information. In computing there can be different data types including integers, characters, and Boolean. Data is often acted on by instructions.

data type

In computer programming, data is divided up and organised according to type, eg numbers, characters and Boolean.
data value A unit of data which is given meaning according to a data type.
database A data store designed in an organised way, making it easier to search for the information you need.
decimal Another name for the number system that contains the digits 0 to 9. Also known as denary or base 10. Decimal fractions are numbers where the fraction is indicated by the use of a full stop, eg 4.1 or 6.3.
denary The number system most commonly used by people. It contains 10 unique digits 0 to 9. Also known as decimal or base 10.
developer Someone who creates computer software.


Any piece of computing hardware.
downloading To copy a file from the internet onto your computer or device.




Files that are encrypted have been altered using a secret code and are unreadable to unauthorised parties.

ethical hacking

Ethical Hacking is also known as Penetration Testing and refers to the process of legitimately testing the security of an IT system using the same tools and methods employed by an illegal hacker. Effective Penetration Testing involves the simulation of a malicious attack against the system under test and should only be conducted by a certificated, ethical hacking professional.


To run a computer program.


The process of a program being run on a computer.



A video calling system used on Apple devices.
FireWire A high-speed connection or interface used to connect external devices to a computer, eg a hard disk, camcorder etc.


Software that controls a device and is not intended to be changed.

flash memory

A form of memory in a computer that uses electronic transistors to store data.
floating point A data value in computer programming used to denote decimal numbers.
frame A single static image in a video and animation.



Gigabyte (GB) - a measurement of file size or storage capacity, 1,024 megabytes, or 1 billion bytes.


Gigahertz. One billion hertz per second = one gigahertz. This is a measure of frequency and is used to describe bus speeds and CPU clock speeds.


Graphical processing unit - a computer chip dedicated to processing graphics.



Gaining unauthorised access to a computer.


The physical parts of a computer system, eg a graphics card, hard disk drive, CD drive etc.

hard drive

A device used to store vast amounts of data.
HD High definition.
HDMI High-definition multimedia interface - a simple connector typically used in home entertainment systems for hi-definition media.

heat sink

A component used on computer motherboards to cool the CPU.
hertz The unit of frequency, symbol 'Hz'. 1 Hz is 1 wave or cycle per second.
HTML Hyper Text Markup Language. The language used to write and display web page documents.
http Hypertext transfer protocol - a request/response standard. Web browsers send requests and websites or servers respond to requests.



A single action that can be performed by a computer processor.

instruction cycle

An instruction cycle (sometimes called a fetch–decode–execute cycle) is the basic operational process of a computer. It is the process by which a computer retrieves a program instruction from its memory, determines what actions the instruction dictates, and carries out those actions

  1. The processor checks the program counter to see which instruction to run next.
  2. The program counter gives an address value in the memory of where the next instruction is.
  3. The processor fetches the instruction value from this memory location.
  4. Once the instruction has been fetched, it needs to be decoded and executed. For example, this could involve taking one value, putting it into the ALU, then taking a different value from a register and adding the two together.
  5. Once this is complete, the processor goes back to the program counter to find the next instruction.
  6. This cycle is repeated until the program ends.


is a characteristic of a product or system, whose interfaces are completely understood, to work with other products or systems, present or future, in either implementation or access, without any restrictions.
integer A whole number - in computing, a data type which represents signed (positive) or unsigned (negative) whole numbers.
integrated circuit A chip, used in many areas of electronic engineering including a computer CPU.
interpreter A program that translates high level programming languages into machine code. Programs can either be interpreted or compiled.


Internet Protocol - A set of rules for communicating over the internet. IP can also stand for intellectual property.



Kbps Kilobits per second (Kbps): a measurement of the speed data is being transferred at.



Latency is the delay time between the moment a memory controller tells the memory module to access a particular memory column on a RAM module, and the moment the data from the given array location is available on the module's output pins.
LED Light-Emitting Diode. LEDs glow when current passes through them.
Linux An operating system, similar to Windows or Mac OS. Linux is free and open-source, meaning anyone can improve it and share their improvements.

logic gate

Circuit components which take several inputs, compare the inputs with each other, and provide a single output based on logical functions such as AND, OR and NOT.
loop A method used in programming to repeat a set of instructions.
lossless A form of compression that encodes digital files without losing detail. Files can also be restored to their uncompressed quality.
lossy A form of compression that reduces digital file sizes by removing data.


machine code

Also called object-code, this is low-level code that represents how computer hardware and CPUs understand instructions. It is represented by binary numbers.
markup language A language used to present and organise text, especially within a HTML document.
MBps Megabytes per second - a measurement of data transfer speed.


1,000,000 hertz - a measure of frequency, or cycles per second.


The part of a computer that stores data.
memory location In computing, this is an address in the primary memory where data values are stored.

memory card

A small storage device that fits into cameras, mobile phones and other handheld devices. They can store several GBs of data and use solid state memory with no moving parts.
molecular Refers to a substance made up of molecules, so it contains small groups of atoms, of a set size, held together by covalent bonds.
molecular biology The field of biology which looks at DNA.
Moore's law The theory, observed by Gordon E Moore, that computer processing power doubles roughly every two years.


The circuit board inside a computer that houses the CPU, memory and connections to other devices.
MP3 A standard audio file format which uses lossy compression. Compatible with most media players. Designed by the Moving picture experts group - layer 3.


network card

A piece of hardware that connects a computer to a network.


A form of computer memory that stores data even when not powered.


off-the-shelf A type of software which is readily available and should be suitable for a large amount of people.

open source

A model for creating technology that promotes free access to its design and makes it free to share.
operation An action performed on data such as arithmetic, logical comparison or concatenation (linking things together in a series).

operating system

The software that runs a computer.


A version of Apple's Mac OS operating system for Apple computers.


An overflow error is caused when the processor does not have enough bytes available to process an instruction.


PC Personal computer.
PCM Pulse-code modulation - a process for digitizing analogue audio and creating an uncompressed audio file.


A piece of hardware that connects to a computer, eg a mouse, keyboard, printer or scanner.


A physical interface on a computer to connect externals such as mice and keyboards. Over a network a port is a point where information is sent through, eg the http port.
procedure A section of computer code that performs a specific task.

programming language

A language used by a programmer to write a piece of software. There are many programming languages.


A set of rules for how messages are turned into data packets and sent across networks.

proxy server

A server that is an interface between the original clients and servers on a network.


A method of writing up a set of instructions for a computer program using plain English. This is a good way of planning a program before coding.
prototype A working model of a design used for testing, development and evaluation.



Random Access Memory (RAM): Memory that is constantly being written to and read from. It does not retain its contents without a constant supply of power, eg when a computer is turned off, everything stored in its RAM is lost.

Raspberry Pi

A low budget, pocket sized computer which is easy to program.


The section of high speed memory within the CPU that stores data to be processed.
resolution The fineness of detail that can be seen in an image - the higher the resolution of an image, the more detail it holds. It is measured in dots per inch (dpi).


Reduced instruction set computing - a type of CPU found in smartphones and tablets.


Read Only Memory (ROM): memory or storage that has data stored on it that cannot be changed.
RSS Rich site summary - a method for delivering website updates to a user without the user having to visit the website itself. Often called really simple syndication.


sample rate How many samples of data are taken per second. This is normally measured in hertz, eg an audio file usually uses samples of 44.1 kHz (44,100 audio samples per second).
SD Standard definition.
server A computer that holds data to be shared with other computers. A web server stores and shares websites. Servers require server software.


Video calling and messaging software developed by Microsoft.


A mobile phone with a powerful processor that is capable of running applications and accessing the internet.


The programs, applications and data in a computer system. Any parts of a computer system that aren't physical.
source code The written code that creates a computer program.
SQL Structured query language - a programming language used to control databases.


The smallest element of a programming language which expresses an action to be carried out.
string A sequence of characters often stored as a variable in a computer program.


The hardware of a computer that stores data long term, such as a memory card or hard drive.


A method of downloading digital media such as audio and video as a temporary file.
streaming Data that is sent in pieces. Each piece is viewed as it arrives, eg a streaming video is watched as it downloads.
switch A device for connecting computers and other network capable devices together to form a network.



A computer device a little smaller than a laptop but with a built-in touchscreen, usually without a keyboard.


Microscopic devices that open and close circuits to communicate electrical signals. CPUs contain millions of transistors. (i7 quad core 1,400 million transistors)
translator Program translators convert program code into machine code to be executed by the CPU. There are three types of translator: interpreter, compiler and assembler.

truth table

Used to assess possible results of a Boolean algebra statement.


USB Universal serial bus (USB): connects peripheral devices to a computer, eg a camera, memory stick, keyboard, mouse or mobile.

USB memory stick

A physically small storage device. It normally plugs into a USB port. They are also called USB sticks, memory sticks, thumb or flash drives. These devices use solid state memory with no moving parts
user interface The means by which a user interacts with a computer or device.
Unicode A system of encoding text in computing widely used on the internet.
uncompressed A file which has not had any data removed through compression.



In a computer program, this is a memory location where values are stored.

video conference

In a computer program, this is a memory location where values are stored.

virtual memory

A section of a computer storage drive which is temporarily used as RAM.


Computer code designed to damage a computer system.
VoIP Voice over internet protocol - a protocol used for communicating voice data over the internet.

volatile memory

The memory used to store computer program data while it is being executed. RAM is the main type of volatile memory. It is volatile because when power is switched off it no longer retains any data.


WAV An uncompressed audio file format developed by Microsoft

web application

An application that runs within a web browser.
web browser An application that displays web pages.
whole number. Any number which does not need a decimal point. Also known as an integer


Microsoft's brand of operating systems, eg Windows 98, Windows XP, Windows Vista, Windows 10 etc.

word size

The size of an instruction a CPU can process. A 16 bit process can process words of up to 16 bits.


XML eXtensible Markup Language (XML): a general-purpose specification for creating custom markup languages.


zero day attack

A ‘zero-day’ (or zero-hour or day-zero) attack or threat is an attack that exploits a previously unknown vulnerability in a computer application or operating system, which developers have not had time to address and patch. The term ‘zero-day’ refers to the fact that the programmer has had zero days to fix the flaw (in other words, a patch is not available). Once a patch is available, it is no longer a ‘zero-day exploit’. It is common for individuals or companies who discover zero-day attacks to sell them to anybody for a variety of purposes.

3.1 Fundamentals of algorithms

3.2 Programming

3.3 Fundamentals of data representation

3.4 Computer systems

3.5 Fundamentals of computer networks

3.6 Fundamentals of cyber security

3.7 Ethical, legal and environmental impacts of digital technology on wider society, including issues of privacy

3.8 Aspects of software development

Glossary and other links

Glossary of computing terms.

AQA 8520: The 2016 syllabus