GCE O/L Information & Communication Technology key terms

Raw, unprocessed facts, figures, symbols or signals with no meaning on their own. Data becomes useful only after it is organised, interpreted or processed into information.

Data that has been processed, organised and given meaning so it is useful for decision-making. Accuracy, relevance and timeliness determine how valuable information is to its user.

The sequence of operations that converts raw data into meaningful output, typically input, processing, storage and output. Manual or automated, it underlies every computer-based information system.

Hardware that sends data or instructions into a computer, such as a keyboard, mouse, scanner, microphone or barcode reader. It converts human actions or physical values into signals the processor can use.

Hardware that presents processed results to the user, such as a monitor, printer, speaker or projector. It converts internal electronic signals into text, images, sound or physical copies.

The main chip that fetches, decodes and executes program instructions and controls the rest of the computer. It contains the control unit, arithmetic logic unit and registers, and speed is measured in hertz.

Volatile working memory that holds programs and data currently in use so the processor can reach them quickly. Its contents are lost when power is switched off, unlike storage.

Non-volatile memory whose contents are written at manufacture or by special equipment and normally only read. It stores firmware such as the start-up instructions used when a computer is powered on.

Small, very fast memory close to the processor that holds recently or frequently used instructions and data. It reduces the average time the CPU waits for slower main memory.

Software permanently stored in read-only or flash memory that controls basic hardware behaviour, such as a computer's start-up routine. It sits between hardware and the operating system and is rarely changed.

System software that manages hardware, memory, files and processes and provides a platform for application programs. It offers the user interface and controls access to resources such as printers and disks.

Small system program that maintains, protects or tunes the computer, for example antivirus scanning, disk defragmentation, backup or file compression. It supports the operating system rather than performing user tasks.

A base-2 number system using only the digits 0 and 1, where each position represents a power of two. Computers use it because circuits can easily represent two distinct voltage states.

The smallest unit of digital data, a single binary digit that is either 0 or 1. Groups of bits represent numbers, characters, images and instructions inside a computer.

A group of eight bits treated as one unit, commonly used to store one character or a small number. Storage and memory capacity are usually expressed in bytes and their multiples.

A base-16 number system using digits 0 to 9 and letters A to F, where each digit stands for four binary bits. Programmers use it as a short, readable way to write binary values such as memory addresses and colour codes.

A rule set that assigns a unique numeric code to each character so text can be stored and exchanged digitally. ASCII covers basic English characters, while Unicode covers most of the world's writing systems.

An agreed set of rules governing how devices format, send, receive and acknowledge data over a network. Without shared protocols, hardware from different makers could not communicate reliably.

A unique numeric label assigned to a device on a network so data can be routed to it. IPv4 uses four decimal groups, while IPv6 uses longer hexadecimal groups to provide far more addresses.

A service that translates human-readable domain names such as example.com into the numeric IP addresses computers use. It works like a distributed directory of the internet.

The full address of a resource on the web, giving the protocol, server name and path, for example https://site.com/page. It tells the browser exactly where and how to fetch a page or file.

A network covering a small area such as one building or campus, where devices are connected by cable or wireless. It allows fast sharing of files, printers and internet access among nearby users.

A network that spans a large geographical area, linking sites across cities or countries, often using public or leased telecommunication lines. The internet is the largest example.

The arrangement of devices and links in a network, such as star, bus, ring or mesh. The choice affects cost, reliability and how easily faults can be found and repaired.

A finite, ordered set of unambiguous steps that solves a problem or completes a task. It may be written as pseudocode or a flowchart before being translated into a programming language.

A structured, language-independent way of writing an algorithm using plain words and common keywords such as IF, WHILE and INPUT. It is easier to read than code and can be translated into any language.

A diagram of an algorithm using standard symbols, such as ovals for start and end, parallelograms for input and output, and diamonds for decisions. Arrows show the order in which steps run.

A named storage location in a program whose value can change while the program runs. It has a data type, such as integer or string, that determines the operations allowed on it.

A named value that is set once and cannot be changed while the program runs, such as the value of pi or a maximum size. It makes programs clearer and prevents accidental alteration.

A classification that defines what kind of values a variable may hold and which operations apply, for example integer, real, character, string or Boolean. It helps the computer store values correctly and use memory efficiently.

An organised collection of related data stored so it can be accessed, managed and updated efficiently. Computer databases are usually controlled by database management software that enforces structure and security.

A single attribute or column of a database table, holding one item of data about each record, such as a surname or date of birth. Each field has a defined data type and size.

One complete row in a database table, made up of all the fields describing a single entity such as one student or one order. Records are added, edited and deleted as units.

A field, or combination of fields, whose value uniquely identifies every record in a table. It prevents duplicate rows and is used to link tables together.

A request that extracts specific data from a database, usually by stating conditions and chosen fields. Results can be sorted, calculated and used as the basis for forms and reports.

The staged process of building an information system, typically analysis, design, development, testing, implementation and maintenance. Each stage produces documented outputs that guide the next stage.

An early investigation that judges whether a proposed system is technically, economically, legally and operationally practical. Its findings help management decide whether to fund the project.

Running a system or program with planned data to find errors and confirm it meets requirements. It ranges from checking individual modules to full system and acceptance testing by users.

Software written to damage, disrupt or gain unauthorised access to a computer system, including viruses, worms, trojans and ransomware. Updated antivirus software and careful behaviour reduce the risk.

A trick that uses fake emails, messages or websites to persuade people to reveal passwords, card numbers or other private data. Users should verify the sender and never follow unexpected links.

Hardware or software that filters network traffic, allowing or blocking connections according to set rules. It helps keep unauthorised users and malware out of a private network.

The process of scrambling data using a key so that only someone with the correct key can read it. It protects information during transmission and when stored on devices.

A duplicate copy of data or programs kept separately so that information can be restored after loss, damage or attack. Regular, tested backups are a basic safeguard against data loss.