In the evolution of all kinds of lamps and lighting generators, LED is known as the most efficient type of lighting sources.
Incandescent lamps (GLS) with a light efficiency of 10 lumens per watt produce heat before producing light. These lamps burn sooner than other kinds of lamps and their life time never exceeds more than 1000 hours. The excessive loss of energy as well as short life time of GLS lamps caused their presence in the market decrease drastically.
The second category of light sources is fluorescent lamps. Although these lamps have better efficiency of 45 lumens per watt and a life time of about 8000 hours, they are not still desirable because they pollute the environment with toxins like mercury.
LED lamps, luminaries and lighting sources with an efficiency of over 100 lumens per watt and a life time of over 40,000 hours, have opened a new horizon for the lighting industry. The capability of designing new lighting systems using LEDs is another advantage of them.