Only a few hundred years ago, the fastest way a piece of news could travel was to be carried by a person on horseback.
Messages sent overseas could only travel as fast as the fastest sailing ship. The breakthrough came with the invention of the electric telegraph and messages in Morse code. The message was sent down a wire in bursts of electric current.
Today, however, images of written documents, sound recordings or television pictures can be flashed around the globe in less than a second by means of satellites and radio communications.
Several satellites, in different orbits, are required to give coverage over the whole globe, and different satellites are used to reflect signals for different media, such as telephone messages and television pictures.
Why are optic fibres so useful in communication technology?
An optic fibre is made of fine strands of glass, along which pulses of light can travel. Light travels much faster than electricity and it is therefore used in optical cables to carry communications for very long distances without electrical interference.
The light travels along tiny glass fibres, usually packed into huge bundles capable of carrying many thousands of messages at the same time.
When you talk on the telephone your voice is turned into laser light signals and sent down very thin fibre glass tubes called optical fibres. Up to 150,000 different conversations can be sent down just one of these optical fibres.
Optic fibre is also used for ornate lighting. Light is reflected down thousands of tiny glass fibres as can be seen on some modern artificial Christmas tree.