Electrical polarity is a term used throughout industries and fields that involve electricity. There are two types of poles: positive (+) and negative (−). This represents the electric potential at the ends of a circuit. A battery has a positive terminal (+ pole) and a negative terminal (− pole). Interconnection of electrical devices nearly always require correct polarity to be maintained. Correct polarity is essential for the operation of vacuum tube and semiconductor devices, many electric motors, electrochemical cells, electrical instruments, and other devices.