The combination of a number of electrical devices and conductors that, when connected together to form a conducting path, fulfil a desired function such as amplification, filtering, or oscillation. A circuit may consist of discrete components or may be an integrated circuit. Some circuits, such as charge-coupled devices, can only be produced in integrated form.

A circuit is closed when it forms a continuous path for current. When the path is broken, as by a switch, the circuit is open. Any constituent part of the circuit other than the interconnections is a circuit element.