A contactor is an electrically controlled switch used for switching electrical power circuits similar to a relay but with higher current ratings. It has three main components - contacts that carry the current, an electromagnet or coil that provides the driving force to close the contacts, and an insulating enclosure housing the contacts and coil. Contactors are designed to directly connect to high-current load devices above 15 amps, unlike relays which are lower capacity and can be normally open or closed. Modern contactors use techniques like vacuum or inert gases to suppress arcs between contacts during opening and closing to prevent damage.