Amplitude The strength of a wave, such as a radio wave.

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, including radio and TV programmes, can pass at once. Broadband internet provides fast upload and download speeds.

Broadcasting The transmission of radio and TV programmes via cables, ground-based transmitters and satellites, and the internet.

Cable television Television that is transmitted through a network of underground cables. Cables link to televisions via special receivers.

Carrier wave A radio wave that can be modulated in order to carry information. Once modulated, a signal is sent to a transmitter.

Cathode-ray tube The picture display technology used in older televisions. It is a sealed glass tube containing “guns” that fire beams at a screen. The beams make coloured dots on the back of the screen glow. The brightness of each dot is controlled by the TV signal. The lines of dots create a full-colour image on screen.

Channel A narrow range of radio frequencies used by a TV or radio station. Audiences tune their receivers to the frequency for the channel that they want.

Closed-circuit television (CCTV) In closed-circuit television, signals are not broadcast at all. Instead, they go directly from the camera to a receiver. CCTV is used for security systems, with the pictures being recorded as well as viewed.

Control room The room in a TV studio where live images and sounds are mixed to create a signal for broadcast.

Frequency The number of wave crests that pass a point each second. Different TV and radio stations are broadcast on carrier waves of different frequencies so they do not interfere with one other.

High-definition TV (HDTV) A high-resolution TV picture with up to 2 million pixels per frame—around five times more than a standard TV.

Interactive television Television broadcasts in which the viewer can send information back to the television station, normally via a telephone or digital cable line. The combination of digital television and a telephone line also allows viewers to access the internet.

Liquid Crystal Display (LCD) A type of picture display. An LCD screen contains a backlight, a layer of liquid crystals and a layer of colour pixels. When electricity passes through the crystals, they act as tiny shutters, varying the amount of light that each pixel transmits.

Marconi, Guglielmo (1874–1937) Italian inventor who, in 1896, became the first person to make a long-distance radio transmission.

Microwaves Super high-frequency radio waves. Microwaves carry signals between transmitters and receivers, and to and from communications satellites.

Modulation The shaping of a radio wave to make it carry information. Modulation is achieved by using an electrical signal to change either the strength of a wave—amplitude modulation or AM—or the frequency of a wave—frequency modulation or FM.

Plasma screen A type of TV screen containing a layer of cells filled with gas. An electric current causes the gas to give off energy, making the cell glow.

Podcast A TV or radio programme produced in a digital format and made available for downloading from the internet on to a computer, tablet, smartphone or portable media player. It gets its name from mixing the words "broadcast" and "pod" (the Apple iPod, is a popular portable media player).

Radio waves A type of invisible energy wave. They can travel through air, space and solids. On their own, radio waves do not carry information, but they can be shaped, or modulated, in order to carry information for a wide range of applications. Radio waves are used in the telephone network, for remote control of machines, and for broadcasting television and radio programmes. TV programmes can alternatively be broadcast along cables, and both radio and TV programmes can be broadcast over the internet.

Receiver A device that detects signals, such as radio waves. For example, a radio receiver picks up radio waves and demodulates them to get back the original electronic signal. It uses a tuning circuit to pick out the signal from one radio station.

Satellite television TV broadcast via satellite. Signals are beamed to a satellite from a ground station. The satellite detects the signals and re-transmits them to receivers on Earth. They are received by aerial dishes pointed towards the satellite from people’s homes.

Streaming A technique for transferring data, including moving images and sounds, as a continuous stream: for example, a broadcast TV programme. With live streaming of TV via the internet, a computer can start displaying the images and sounds before the entire file has been transmitted.

Studio A room in which a TV or radio programme is recorded to be broadcast.

Television camera A camera that takes 25 to 30 photographs (frames) a second and creates electronic signals representing the pattern of colours in the frame.

Terrestrial television TV broadcast by radio from ground-based transmitters. The signal can be detected by the aerial of any receiver within range of the transmitter.

Transmitter An electronic device that gives out signals such as radio waves. A carrier wave is fed to a transmitter, which turns it into a radio wave.

UHF (Ultra-high frequency) UHF radio waves are used for radio and television broadcasting, cordless phones, satellite telecommunication links, mobile phones and many other applications. They travel by "line of sight": they are blocked by hills and large buildings.

Waveband A range of radio wavelengths, for example long wave and short wave. Short waves bounce between the Earth’s surface and a layer of the atmosphere called the ionosphere. Medium waves bounce off the bottom of the ionosphere. Long waves travel flat above the surface of the Earth.

Wavelength The distance between two crests or two troughs on a train of waves.

Webcasting The broadcasting of television and video pictures over the internet. The pictures are first converted into a digital video format and then made available on a website.

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).

Zworykin, Vladimir (1888–1982) Russian-American inventor who patented the cathode-ray tube television in 1928.

Consultant: Chris Oxlade