Acceptable Use Policy (AUP)

A policy that communicates to users what specific uses of computer resources are permitted.

Access Control List (ACL)

A clearly defined list of permissions that specifies what actions an authorised user may perform on a shared resource.

Accessible Rich Internet Applications (ARIA)

A specification by the World Wide Web Consortium (W3C) for adding semantics and other metadata to HTML to aid those who use assistive technology.

Active Directory (AD)

A product developed by Microsoft to manage users, computers and other devices on a network. It is provided as part of the Microsoft Windows Server operating system.

Address Resolution Protocol (ARP)

A TCP/IP protocol, used with the command line tool of the same name, to determine the MAC address that corresponds to a particular IP address.

Advanced Encryption Standard (AES)

An encryption standard created in the late 1990s, which utilises a symmetric block cipher, that uses a 128-bit block size and either a 128, 192 or 256-bit key size.

American Standard Code for Information Interchange (ASCII)

A character encoding that uses numeric codes in binary to represent characters. These include upper and lowercase English letters, numbers, and punctuation symbols.

Apple Filing Protocol (AFP)

A protocol developed by Apple for sharing files over a network. It was used in Apple's Macintosh operating systems up to macOS 10, however, it has mostly now been replaced by the standard Server Message Block (SMB) protocol.

Application Program Interface (API)

A library of related programme code available for programmers to use.

Application Service Provider (ASP)

A company that offers applications and services over the internet.


A network of computers, or bots, as they are sometimes referred to, which are infected with malware and can be controlled remotely to, for example, carry out a distributed denial of service (DDoS) attack.

Cascading Style Sheet (CSS)

A language that is used to provide the look and feel to the structure of a web page, for example, the colour and font used for paragraph text.

Central Processing Unit (CPU)

A microprocessor that acts as the brain of a computer, containing the circuitry necessary to interpret and execute program instructions such as arithmetic, logic, controlling and input/output operations.


Ciphertext is the result of plaintext being encrypted using an algorithm, known as a cipher.

Confidentiality, Integrity and Availability (CIA)

A security model that can be used to guide an organisation's policies on information security. Also sometimes known as the CIA triad or AIC triad.

Content Management System (CMS)

A web based application that allows non-technical users to manage the content of a website. These applications are built using web technologies such as PHP or the .NET Framework and utilise a database, for example, MySQL, PostgreSQL, Oracle or SQL Server, to store the website information.

Create, Read, Update and Delete (CRUD)

Refers to the possible ways to operate on stored data, such as in a database.


A tool used by a number of Linux distributions for automatically running tasks at a scheduled time.


An area of the internet that cannot be indexed by search engines such as Google and are not normally accessible via a standard web browser, but instead through specialist software. A Darknet can be used for harmless means, such as for a corporate website, as well as illegal means, such as hacking and file sharing forums where users wish to stay anonymous.

Database Management System (DBMS)

Software designed to define, manipulate, retrieve and manage data in a database.

Demilitarized Zone (DMZ)

A physical or logical subnetwork that contains and exposes an organisation’s external-facing services to an untrusted network, such as the Internet. Its purpose is to add an additional layer of security to an organisation’s local area network (LAN). The untrusted network can only access what is in the DMZ, whilst the rest of the network is secured behind a firewall. Also sometimes known as a perimeter network.

Desktop as a Service (DaaS)

An operating system and other software provided on a subscription basis. A provider of this type of service will use virtualisation technology to create virtual desktops on physical infrastructure within data centres. An end user will access a virtual desktop via their computer.

Document Object Mode (DOM)

The DOM is an API, or interface, which is loaded in a web browser, that allows for interaction with HTML and XML documents. It represents these documents in a tree structure, where each node is an object representing a part of the document.

Domain Name System (DNS)

Domain names serve as memorable names for websites and other services on the Internet. DNS converts domain names into IP addresses, which are then used to access the corresponding service on the Internet.

Double Data Rate (DDR)

A type of computer memory, which is an advanced version of SDRAM, that can transfer data twice as fast as regular SDRAM chips. This is because DDR memory can send and receive signals twice per clock cycle.

Double Data Rate 2 (DDR2)

An improved version of DDR memory that is faster and more efficient.

Double Data Rate 3 (DDR3)

A type of memory that is similar to DDR2 RAM, but uses roughly 30% less power and can transfer data twice as fast.

Double Data Rate 4 (DDR4)

A type of memory that has faster data transfer rates and larger capacities than DDR3. It can also operate at a lower voltage, making it more power efficient.


The practice of researching and publishing private or identifiable information on the internet, regarding an individual or organisation.

Drive-by Download

A drive-by download is where something is downloaded from the internet to a computer without the prior knowledge of the user, or where a download is authorised by the user but the full consequences of the download are not understood.

Dynamic Host Configuration Protocol (DHCP)

A protocol that automatically assigns a unique IP address to each device that connects to a network.

Dynamic Link Library (DLL)

A type of file which contains a library of functions and other information that can be accessed by a Microsoft Windows based piece of software.


The process of converting plain text into ciphertext to prevent unauthorised access.

Extensible Application Markup Language (XAML)

A markup language developed by Microsoft, that is used for creating application interfaces.

File Transfer Protocol (FTP)

A protocol that works at the application layer, which is used to transfer files over a network connection.

File Transfer Protocol Secure (FTPS)

A protocol that works at the application layer, which is used to transfer files over a network connection, using FTP over an SSL or TLS connection.


A network security system, which monitors traffic to and from a computer network. It has the ability to allow or block traffic depending on a set of predefined rules. Firewalls can be implemented using software, hardware or a combination of the two.

First In, First Out (FIFO)

A method of processing and retrieving data. In a FIFO system, the first items entered are the first ones to be removed.

General Data Protection Regulations (GDPR)

European Union law that specifies a broad set of rights and protections for personal information of EU citizens.


A computer system or portion of a network that has been set up purely for the purposes of attracting intruders. As there are no legitimate users in a system such as this, unauthorised activity is easy to spot.


An electronic device that sits at the centre of a star bus topology network, providing a common point for the connection of network devices. Hubs repeat all information it receives to all connected devices and have been replaced by switches.

Hyper-Text Markup Language (HTML)

A language that is used to provide the structure of web pages, using tags to define different parts of the page structure, for example, <h1> tags to denote the largest headings, or <p> tags for paragraphs of text.

Hyper-Text Transfer Protocol (HTTP)

A network protocol that facilitates the transfer of documents, such as web pages, on the web, typically between a web browser and a server.

Hyper-Text Transfer Protocol Secure (HTTPS)

A secure version of HTTP, that encrypts communications between a client and server, using SSL or TLS.

Immutable Object

A computer programming term used to describe an object whose state cannot be changed after it has been defined.

Infrastructure as a Service (IaaS)

Infrastructure, such as servers and storage, provided on a subscription basis. A provider of this type of service will use virtualisation technology on physical infrastructure within data centres.


In Object-Oriented Programming, Inheritance refers to the ability of an object to take on, or inherit, the properties of another object.

Institute of Electrical and Electronics Engineers (IEEE)

An American based professional associated, which develops standards for electronics and computer science.

Integrated Development Environment (IDE)

A piece of software that provides a means to create software and web applications. They generally include a source code editor, for programming purposes, a compiler where needed, for building an application and debugging tools, to aid in the resolution of bugs or problems with an application.

Integration Platform as a Service (iPaaS)

A subscription based service, which provides tools to enable the integration of data, applications and processes hosted on different physical and cloud services.

Internet Control Message Protocol (ICMP)

A TCP/IP protocol used to handle many low-level functions, such as error reporting. ICMP messages usually comprise of request and response pairs, for example, echo requests and responses, router solicitation and responses, and trace route request and responses. ICMP messages are connectionless.

Internet Information Services (IIS)

Web server software, that is provided by Microsoft and available on various versions of Microsoft Windows, including Windows 10 and Windows 11, as well as Windows Server.

Internet Protocol (IP)

The Internet standard protocol that handles the logical naming for the TCP/IP protocol using IP addresses.

JavaScript Object Notation (JSON)

A text-based data interchange format designed for transmitting structured data. It is most commonly used for transferring data between web applications and web servers.


A network authentication protocol developed by MIT to enable multiple brands of servers to authenticate multiple brands of clients.

Last In, First Out (LIFO)

A method of processing data in which the last items entered are the first to be removed.

Lightweight Directory Access Protocol (LDAP)

A protocol used by a number of operating systems and applications to access directories.

Linux, Apache, MySQL, and PHP (LAMP)

The Linux operating system, Apache web server, MySQL database, and PHP web scripting language can be used together to create a fully functioning web server.

Local Area Network (LAN)

A network of connected devices, including computers and printers, that exist within a specific location.

Logical Block Addressing (LBA)

An addressing scheme that acts as an interface between the operating system and storage devices. It presents storage chunks on a storage device to the operating system as a sequence of blocks. This saves the operating system from having to deal with the detail of how the storage space is arranged on a hard disk or solid-state disk. Logical Block Addressing is inherant to all operating systems and mass storage devices.

Mac OS, Apache, MySQL, and PHP (MAMP)

The Mac OS operating system, Apache web server, MySQL database, and PHP web scripting language can be used together to create a fully functioning web server.


Malware is the collective name given to software that has been developed to disrupt or damage data, software or hardware, as well as gain unauthorised access to computer systems.

Media Access Control Address (MAC Address)

A hardware identification number that uniquely identifies each device on a network. The MAC address is manufactured into every network card, such as an Ethernet card or Wi-Fi card, and therefore cannot be changed.

Metropolitan Area Network (MAN)

A Wide Area Network that is limited to a municipal area.

Model-View-Controller (MVC)

A design pattern utilised in software development, which is used to implement software interfaces, data and controlling logic, separating out the business logic from the display.

Multi-Function Device (MFD)

A single device that consolidates the functions of multiple document handling devices, such as printing, copying, scanning, and faxing.

Mutable Object

A computer programming term used to describe an object whose state can change after it has been defined.

Network Address Translation (NAT)

A way of converting a system's IP address into another IP address before sending it out to a larger network. A network using NAT provides the systems on the network with private IP addresses. The system running the NAT software has two interfaces, one connected to the network and the other connected to the larger network. The NAT program takes packets from the client systems bound for the larger network and translates their internal private IP address to its own public IP address, enabling many systems to share an IP address.

Object-Oriented Programming (OOP)

A programming paradigm based on the concept of “objects”, which may contain data, in the form of fields or attributes, and behaviours, in the form of procedures or methods. Computer programs created in this way are usually made up of multiple objects that interact with one another.

Open Source

Software that is said to be open source refers to the fact that the original source code used to create it is made freely available to view, modify, enhance and redistribute.

Personal Area Network (PAN)

An interconnection of devices to facilitate the exchange of information in the vicinity of a person. This is over a short distance of less than 33 feet or 10 metres and typically utilises wireless technologies, such as Bluetooth.


An attempt to gain sensitive information, such as user account and bank details, for malicious reasons, via an electronic communication, such as email, purporting to be from a trustworthy source. This might be to steal someone’s identity, for financial gain, or both.

Platform as a Service (PaaS)

A subscription based service which provides a managed environment of hardware and software. This type of service is popular with application developers as it removes the need to maintain the complex infrastructure required.


In Object-Oriented Programming, Polymorphism refers to the ability of a programming language to process objects differently depending on their data type or class.


In Computing there are two types of port, hardware ports and networking ports. A hardware port serves as an interface between a computer and peripheral devices, such as a monitor, printer, keyboard and mouse. A port is a part of a computer that these devices connect to. A networking port is a communication endpoint. It is a logical construct that identifies a specific process or type of network service, at the software level, within an operating system. Ports have a port number associated with them and relate to specific transport protocols, for example, port 80 handles HTTP traffic.

Random Access Memory (RAM)

Memory that can be accessed randomly, either for reading or writing, without accessing preceding parts of it.

Read-Only Memory (ROM)

Memory that can be read from but to written to. Often described as non-volatile memory.

Redundant Array of Independent or Inexpensive Disks (RAID)

A method for creating a fault tolerant storage system. RAID uses multiple hard drives in various configurations to offer different levels of speed and data redundancy.

Remote Desktop Protocol (RDP)

Protocol used for Microsoft's Remote Desktop tool.

Secure File Transfer Protocol (SFTP)

Uses SSH to provide the encryption for secure file transfer.

Secure Shell (SSH)

An encrypted remote terminal connection program, used to remotely connect to a server. SSH uses asymmetric encryption, however, it generally requires an independent source of trust with a server, such as manually receiving a server key, to operate.

Secure Sockets Layer (SSL)

A protocol developed for transmitting private documents over the internet. It works by using a public key to encrypt sensitive data. This encrypted data is then sent over an SSL connection and then decrypted at the receiving end using a private key. Deprecated by Transport Layer Security (TLS).

Shielded Twisted Pair (STP)

A Special kind of copper telephone and Local Area Network wiring that adds an outer layer, or shield, to reduce the potential for electromagnetic interference. Twisted pair wiring is where two conductors of a single circuit are twisted together to improve electromagnetic compatibility.

Simple Mail Transfer Protocol (SMTP)

The main protocol used to send email over the internet.

Simple Network Management Protocol (SNMP)

A set of standards for communication with network devices, such as switches and routers, connected to a TCP/IP network.

Single-Board Computer

A computer built on a single circuit board, which incorporates a processor, memory, input and output capabilities, along with many other features of a regular computer.


An attempt to gain sensitive information, such as user account and bank details, for malicious reasons, via an SMS message, purporting to be from a trustworthy source. This might be to steal someone’s identity, for financial gain, or both.

Social Engineering

The use of deception to manipulate an individual into divulging confidential or personal information that may be used for fraudulent purposes.

Software as a Service (SaaS)

A subscription based service which provides a managed environment for web based applications.

Software Development Kit (SDK)

A collection of software development tools that facilitate the creation of software, which can include a software framework, compiler and debugger.

Software Development Lifecycle (SDLC)

A process used by the software industry to design, develop and test high quality software. The Software Development Life Cycle typically consists of stages such as, planning and requirements analysis, definition of requirements, design, build, test, deploy and maintain. There are a number of different Software Development Life Cycle models that are used today, including the waterfall model, the iterative model, the spriral model, the V-medel and the big bang model.


Spoofing is a fraudulent or malicious activity whereby a communication is sent from an unknown source disguised as a source that is known to the receiver. E-mail spoofing is a particular type of spoofing where the header of an e-mail is forged to appear as though it from a particular sender, but instead is from an unknown source.

Structured Query Language (SQL)

A language created by IBM that relies on simple English statements to perform database queries. SQL enables databases from different manufacturers to be queried using a standard syntax.


An electronic device that provides a common point for the connection of network devices, which replaced Hubs. A switch will learn the MAC address of all connected devices when they first connect. This means that it can forward data to the correct device, rather than to all connected devices, as with a Hub.

Transmission Control Protocol (TCP)

A connection oriented protocol used with TCP/IP, where a connection between the client and the server must be established before data can be transmitted.

Transmission Control Protocol/Internet Protocol (TCP/IP)

A set of communication protocols, developed by the U.S. Department of Defence, which enable dissimilar computers to share information over a network.

Transport Layer Security (TLS)

An encryption protocol that is used to securely connect between clients and servers, such as when a web browser securely connects to a website. This replaces Secure Sockets Layer (SSL).

Uninterruptible Power Supply (UPS)

A device which provides continuous power to a computer system whilst it is powered on. It protects against power outages.

Universal Serial Bus (USB)

An external serial bus interface standard for connecting devices such as, keyboards, printers, and scanners, along with many others, to a computer. It enables hot swapping of devices.

Unshielded Twisted Pair (UTP)

A popular cabling for telephone and computer networks composed of pairs of wires twisted around each other at specific intervals. The twists serve to reduce interference, or crosstalk, as it is sometimes known. The more twists, the less interference. The cable has no metallic shielding to protect the wires from external interference, unlike Shielded Twisted Pair (STP). UTP is available in a variety of grades, called categories.

User Datagram Protocol (UDP)

A protocol in the TCP/IP protocol suite for the transport layer that does not sequence packets. It is a connectionless protocol that is “fire and forget” in nature.

Virtual Learning Environment (VLE)

A system for delivering learning material via the web. Its purpose is not to replace face to face teaching, but to enhance it, with the use of various activities that they provide. VLEs are also a means to share resources with its users, such as files and web links.

Virtual Local Area Network (VLAN)

The segmentation of a physical local area network into multiple discreet networks without having to include additional hardware. A common feature of managed switches enables a single switch to support multiple logical broadcast domains, which facilitates the creation of VLANs.


An attempt to gain sensitive information, such as user account and bank details, for malicious reasons, via the telephone, purporting to be from a trustworthy source. This might be to steal someone’s identity, for financial gain, or both.

Wide Area Network (WAN)

A network of connected devices, including computers and printers, similar to a LAN, but not limited to a single location.

Windows, Apache, MySQL, and PHP (WAMP)

The Windows operating system, Apache web server, MySQL database, and PHP web scripting language can be used together to create a fully functioning web server.

Wireless Access Point (WAP)

Connects wireless network nodes to wireless or wired networks. Many WAPs are combination devices that act as high-speed hubs, switches, bridges, and routers, all rolled in to one.

Wireless Local Area Network (WLAN)

A network that allows devices to connect and communicate wirelessly.

World Wide Web Consortium (W3C)

An international body that maintains web-related rules and frameworks, comprising of over 350 member organisations, which jointly develop web standards, run outreach programs, and maintain an open forum for talking about the Web.