Unlike conventional light sources (light bulbs, fluorescent lamps, discharge lamps …) LEDs do not burn out suddenly, but gradually decrease the illumination intensity. LEDs duration equals the number of hours until the LED illuminates with the 70% of its original brightness. Good quality LEDs used in well-designed lamps and lighting systems achieve lifetime of 30 000 – 50 000 hours. For example, a standard bulb may run for about 1,000 hours and fluorescent tubes over a period 8000-10000 hours. The quality and quantity of light and LEDs lifetime is strongly dependent on temperature. LEDs must be used in lighting systems transferring heat from the diode structures. These can be either dedicated heat sinks or a suitably designed lamp housing.