Traditionally, they have been used as indicators on electrical devices, such as standby lights on TVs. This was because LEDs were available only in red, but recent advances mean that other colours are now available, and the light emitted is much brighter.
White light (used for general lighting) using LEDs can be created via a number of techniques. One example is mixing red, green and blue LEDs.
It is suggested that LEDs can last for up to 100,000 hours, compared with the 1,000 hours of traditional incandescent light bulbs and compact fluorescent lamps' (CFLs) 15,000 hours.
The technology is also much more energy-efficient, using up to 90% less energy than incandescent bulbs.
The long lifespans and low energy use make LEDs economically attractive because even though the fittings cost more, the running and maintenance bills are lower.