Computer Science key terms

An operation that makes a file available to a program for a chosen purpose, such as reading or writing.

Software whose licence provides access to its source code and permits users to modify it under stated conditions.

A value on which an operator acts. In 6 + 5, the operands are 6 and 5.

System software that manages a computer’s hardware and resources and provides an environment in which applications can run.

A symbol or keyword that performs an operation on one or more values.

A storage medium read using a laser, such as a CD, DVD or Blu-ray disc.

Storage that uses a laser to read data from an optical disc, such as a CD, DVD or Blu-ray disc.

A logical operator that produces 1 when at least one input is 1, including when both are 1.

A logic gate whose output is 1 when at least one input is 1.

The result produced by a program or system, such as a displayed answer, a warning sound or an updated file.

An error that occurs when a numerical result is too large to fit in the available number of bits.

An error occurring when a calculation produces a result too large to be represented using the number of bits available.

The execution of different instructions or parts of a task at the same time, using multiple processing units.

A named input in a subprogram definition that receives data when the subprogram is called.

A mesh arrangement in which not every pair of devices has a direct connection.

One traversal through the relevant items in a list. In bubble sort, a pass compares successive adjacent pairs.

A secret sequence of characters entered to gain access to an account or system.

A computer in a peer-to-peer network that can both request resources from other computers and provide resources to them.

A network arrangement in which computers share resources directly without a dedicated central server; each peer can request and provide resources.

An authorised, simulated attack on a computer system to identify security weaknesses so they can be corrected.

A hardware device connected to a computer to provide functions such as input or output, for example a keyboard or printer.

Data that identifies, or can be used to identify, an individual, such as their name, address or telephone number.

A unit of data equal to 1,000 terabytes using the decimal convention.

A social engineering attack using fraudulent messages that appear to come from a trusted source to trick recipients into revealing information or taking unsafe actions.

Measures that protect devices, storage media and network equipment from unauthorised physical access, theft or damage.

The smallest individual element of a bitmap image, representing one colour.

The value assigned to a digit’s position in a number. In two-digit hexadecimal, the left position represents sixteens and the right position represents ones.

Readable, unencrypted data.

How faithfully a digital sound recording reproduces the original sound when played.

Post Office Protocol: rules for downloading received emails from an email server to a client, normally removing them from the server.