AQA GCSE Computer Science key terms

A division of network communication tasks with a particular responsibility within a layered model.

Using several complementary security measures so that another defence can help if one fails.

A node with no children. In a Huffman tree, each leaf represents a character.

A question concerning what the law permits, prohibits or requires, including responsibility when harm occurs.

A check that the number of characters in a string meets a requirement, such as a minimum length.

An ordering of strings like dictionary order, determined by comparing characters from left to right.

The period during a program’s execution for which a variable exists.

An algorithm that checks items one at a time, in sequence, until the target is found or the end of the list is reached. It works on sorted or unsorted data.

A network that usually covers a relatively small geographical area and is often owned and managed by one person or organisation.

Storage of data on a device attached to or within the user's computer, such as an internal SSD or an external hard drive.

A variable whose scope is restricted to the subroutine in which it is defined.

An operation that moves every bit a specified number of positions left or right, fills vacated positions with zeros and discards bits moved beyond the available positions.

An operator that works on Boolean values to produce a Boolean result, such as NOT, AND or OR.

A diagram using standard logic gate symbols and connecting wires to show how Boolean inputs produce an output.

A diagram showing logic gates and the connections that carry signals between them.

A mistake in an algorithm’s instructions that causes incorrect behaviour even though the instructions can be executed.

A component that applies a logical operation to one or more Boolean inputs to produce a Boolean output.

The statements executed during each repetition of a loop.

A compression method that allows the original data to be restored exactly when it is decompressed.

Compression that permanently removes some data to reduce file size; the exact original cannot be recovered from the compressed file.

A programming language closely related to a processor’s instructions and architecture, giving the programmer direct control over hardware. Machine code and assembly language are low-level languages.

A physical address embedded within a device’s network adapter that identifies that adapter on a network.

Allowing or blocking a device’s access to a network according to its network adapter’s MAC address.

Instructions encoded in binary that a processor can execute directly.

Designed for a particular processor architecture rather than being readily usable across different processor types.

A type of secondary storage that uses magnetic fields to represent binary 0s and 1s.

Memory directly accessible by the CPU, excluding cache and registers. RAM and ROM are examples.