21 of the Computer Science glossary’s terms, each with the part of the syllabus where you first meet it.
An automatic check that input data is reasonable and follows set rules (for example present, of the correct type, within a range, or of the correct length or format) before a program uses it.
A portion of the labelled data kept out of training and used to compare models or hyperparameter values, separate from the test set used for the final evaluation.
A named storage location in memory that holds a value which can change while the program runs.
A text data type, written VARCHAR(n), that stores up to n characters, using only as much space as each value needs plus a small marker recording its length.
An image stored as a list of shapes (lines, curves, polygons and text) described by coordinates and properties such as colour and line width, which the computer draws when the image is displayed.
A situation in which a customer finds it difficult or expensive to move to a different provider, because their systems and data depend on features, formats or services that only the current provider offers.
Increasing a system's capacity by adding resources, such as processor cores, memory or storage, to the existing server.
A named query stored in the database whose result can be used in other queries as if it were a table.
A logical network created by configuring switches, so that a group of devices behaves as one separate LAN and broadcast domain whatever their physical location or switch.
A software-based computer that runs its own operating system and applications, using hardware resources shared out by a hypervisor on a physical computer.
A technique in which the operating system uses part of secondary storage as if it were extra RAM, so that programs can use more memory than is physically installed.
An encrypted connection across a public network, usually the internet, that lets a remote device or network communicate as if it were directly connected to a private network.
Technology that places a person in a fully computer-generated, interactive environment, usually through a headset that tracks the movements of their head and hands.
A view that stores only its defining query; each time the view is used, the DBMS runs the query against the base tables, so the result is always up to date.
The use of software to create virtual versions of hardware resources, so that one physical computer can behave as several separate computers, or so that resources appear larger or simpler than they really are.
Malware that inserts copies of itself into other files or programs and runs when an infected file is opened, so it spreads only when users share and open infected files.
Adding a VLAN identifier to each Ethernet frame sent across a trunk link between switches, so that frames from several VLANs can share one link and stay separated.
The transmission of voice calls as data packets over an IP network such as the internet, instead of over the traditional telephone network.
A subprogram that carries out an action but returns no value to its caller; in Java its return type is written void.
Memory that loses its contents when the power supply is removed.
A weakness in hardware, software, configuration or human behaviour that an attacker could use to gain unauthorised access, steal or change data, or disrupt a service.