What lights are used on a plane?

A modern passenger airliner will have several external lights.

Taxi lights- These are usually mounted on the Nose Landing Gear or the Nose and maybe another set on the inboard wings. The purpose of these are to light the runway during taxi so the pilots can see where to turn.

Navigation lights - The AC has colored lights so other pilots can see the aircraft and know which way the AC is going. These are usually mounted on the wing tips but for helicopters and other unusually shaped airplanes they can be mounted on sides of fuselage or top. RED light was mounted on the Left wing and GREEN light on the Right wing. At night it is hard to tell which direction a plane is flying because your plane may be going faster or slower than the other one. Therefore, if you see a RED light, you know you are looking at the aircraft's Left wing and he will be moving to your Right.

Logo Light - Commercial airliners have a light that shines on their company logo on the tail. It is only for advertisement.