A Voltage regulator generates a fixed output voltage that remains constant regardless of changes to its input voltage or load conditions. Voltage regulator reduces the incoming voltage to the desired output level and dumps the excess energy as heat.
This is the basic L7805 voltage regulator. It is a three-terminal positive regulator (One for input, one for output and the middle one as ground) which has a 5V fixed output voltage. It can output a maximum current of 1.5A.