The simplest complete circuit is a piece of wire from one end of a battery to the other. An electric current can flow in the wire from one end of the battery to the other, but nothing useful happens.

Series and Parallel Circuit Series and parallel circuits are two fundamental configurations in electrical circuits, each with distinct characteristics that affect how electricity flows through them.

A parallel circuit is way of connecting components on separate branches, so the current can take different routes around the circuit. The current is different in different parts of a parallel circuit.