The properties of optical fibre make it ideal for many applications. Bundles of fibres can be used for lighting inaccessible areas (or making table decorations), or for medical endoscopes. Fibres that are sensitive to environmental changes such as temperature can be used as sensors.

However, by far the largest use of optical fibre is for communications. By sending pulses of light from a source at one end of the fibre to a detector at the other, information or digitised voice and video can be transmitted great distances.

Nowadays, when you make a phone call, the sound of your voice will almost certainly have been digitised and converted into light to travel, for at least part of its journey, down an optical fibre. Subsea optical fibre cables link all the continents of the world, in most developed countries all trunk routes (between exchanges) are now cabled with optical fibre.

These telecommunication applications require lots of information (high bandwidth) to be sent long distances so singlemode fibre (with its low modal dispersion) tends to be used for these applications.

As computers process information faster the networks that link them need to work faster. Increasingly, fibre is being used within computer local area networks (LANs) to help speed the transfer of information between workstations. These datacommunication connections usually have lower bandwidth requirements over shorter distances enabling multimode fibre to be used in these applications.