Protective coatings are a simple way to reduce corrosion, by limiting the exposure of the metal to a corrosive environment.
Paint is a very common protective coating, but tar, pitch, bitumen and plastics are also used.
An important consideration for protective coatings is to ensure the coating is well adhered to the metal, and that it remains intact or is regularly repaired/recoated.
A further form of protective coating is to plate a coat of another metal onto the surface of the metal you wish to protect. One type of this coating is known as galvanising, where zinc is plated onto iron or steel. In the case of galvanising, the zinc acts as an anode and corrodes preferentially to the iron or steel.