Bell, Alexander Graham (1847–1922) Scottish-American inventor who invented the telephone in 1876.

Bluetooth A wireless technology, used in some microphones, phones and other computing devices, for transmitting and receiving signals over short distances using short-wavelength ultra-high frequency (UHF) radio waves.

Broadband A high-speed communications link along which multiple streams of data can pass at once. Broadband internet provides fast upload and download speeds.

Coaxial cable An insulated copper wire along which signals are sent as pulses of electricity. Coaxial cables are used in TV, telephone and computer networks.

Email A system for sending messages almost instantly between any two internet users. Email is short for “electronic mail”.

Fax Data sent between two machines via a telephone line. Fax is short for “facsimile”. A fax machine scans a document, detects its ink pattern and sends this as a signal down a phone line. The receiving machine reads the signal and rebuilds the document.

Hyperlink A reference to another web page, website or document—often represented by a coloured or underlined word, phrase or symbol—that a reader can follow by clicking on it on their computer, or touching it on their tablet or smartphone touchscreen. It is often simply called a link.

Internet A communications network that links computers around the world. Most computers connect to an internet service provider via a telephone or cable line. Internet use falls into email and the world wide web.

LAN A local area network. A LAN uses wireless links or cables to enable communication between all the computing devices—including personal computers, tablets, smartphones and game consoles—in a certain area. Each user connects to the LAN via a central access point, called a switch or hub.

Mobile operating system (mobile OS) An operating system (a set of software that controls computer hardware) designed for touchscreen mobile devices, including smartphones and tablets. Examples include iOS, developed by Apple Inc., Android, developed by Google, and Windows Phone, developed by Microsoft (now discontinued).

Mobile telephone A wireless telephone that connects to the telephone network by radio. The landscape is divided into cells, each with a fixed transmitter and receiver that mobile phones connect to.

Modem A device that connects computers to the internet via a cable or telephone line. It converts analogue signals from the line into digital signals and back again.

Multiplexing A technique that increases the amount of data a network can carry. It does this by merging data streams into one large signal to be carried down a single cable. At the other end, the data is sorted into separate streams.

Network Two or more computers, phones or other devices connected so they can share data. Wireless networks connect these devices using radio waves instead of cables.

Offline Not being connected to the internet, or another computer network.

Online Being connected to the internet, or another computer network.

Optical fibre cable A cable that carries signals as pulses of light along a thin glass fibre.

Packet switched network A network in which data, messages or other digital information is sent in packets, rather than in one continuous flow—in which case a circuit switched network is used. Normal telephone calls, live audio or video are sent by circuit switching, but emails and web pages are usually sent by packet switching.

Satellite A device that has been launched into space and orbits the Earth. Communications satellites relay radio signals between ground stations on Earth.

Search engine A software system designed to search for information on the world wide web. It works by using an automated "web crawler", or "spider", which continuously browses the web, storing information about the pages it comes across. Google and Bing are examples of search engines.

Server A computer that holds large amounts of data, accessed by all the computers on a network.

Smart speaker A voice command device and wireless speaker powered by a virtual (or digital) assistant (such as Amazon's Alexa or Apple's Siri), software that understands natural language voice commands and performs tasks. Using Wi-Fi and Bluetooth, such tasks include streaming audio and video, making calls or sending texts, providing news and information, setting reminders and controlling smart home devices such as lights, thermostats, sprinklers, garage doors and home security.

Smartphone A mobile telephone that also allows access to the internet, takes photographs and has many other functions.

SMS A short message service, often called a text message, or simply a text, which is exchanged between mobile phone users. In 2010, more than 6 trillion text messages were sent.

Social media The online interaction between people, in which they create, share or exchange information (for example, text, pictures or videos) via the internet. Social media technologies include creating weblogs (or "blogs" for short), microblogging (such as Twitter), collaborating with others to create or modify a website (such as Wikipedia), social networks (such as Facebook or Google+) and internet forums: taking part in online discussion sites.

Telecommunications (telecoms) The sending and receiving of information using electricity, radio waves or light. The information can be phone calls, radio programmes, television pictures or computer data. Most forms of telecommunication require transmitting and receiving machines, and a network to link them together. All information is turned into signals that can travel through the network.

Telephone (phone) A device that transmits speech over long distances. Dialling sets up a connection between two telephones. A microphone turns speech into electrical signals, which are sent down the line to another receiver. Here, a speaker turns the signals back into sounds.

Telephone exchange A place where telephone lines are linked. All the local exchanges in one area are linked to a main exchange, which is linked to other main exchanges. Mobile telephone networks and internet service providers are also linked to exchanges.

WAN A wide area network. A WAN is used to connect various computing devices or transmit data over long distances and between different LANs and other smaller networks. The internet is a WAN.

Web browser A software application for retrieving information resources on the world wide web, often called simply a browser. An information resource is identified by a Uniform Resource Locator (URL), more commonly known as a web address. The most popular web browsers are Google Chrome, Microsoft Edge, Safari, Opera and Firefox.

Webcam Short for world wide web camera, a webcam is a video camera that feeds live ("real time") images through a computer to a computer network by streaming media technology.

Website A collection of information, such as text and images, stored on the internet.

Wi-Fi Ultra-high frequency (UHF) radio waves that enable computing devices—including personal computers, tablets, smartphones and game consoles—to connect to the internet via a wireless network access point or "hotspot". Indoors, this has a range of about 20 metres (66 feet).

World wide web A huge information-gathering system. Often simply called the web, it allows one computer connected to the internet to ask for and copy files from another computer.

Consultant: Chris Oxlade