In a relay, there can be multiple normally open contacts, normally closed contacts, and switching contacts. The normally open contact is in the disconnected position when not powered on, the normally closed contact is in the connected position when not powered on, and the switching contact can switch between the normally open and normally closed states.

The main function of automotive relays is to control high currents, as directly controlling high currents through switches may generate electrical sparks and cause danger. Automotive relays belong to switches that control high current with low current, and are a type of electrical component in automotive electrical systems.