Today we live in a world with many facilities available at just a click away. Can you imagine a world without light and electricity now? We now wonder how it was possible for humans to live without light! Sunlight is the most easily accessible source of available light for us. The earliest form of artificial light was fire. In ancient times, the first step towards the development of civilization is said to be the discovery of fire. Early humans made fire by rubbing two flint stones, and then later by burning wood, oil, candles, etc. Today we produce light mostly by using electricity.