In electrical circuits, ground is a point that has no measurable electrical charge, and to which current can flow to either complete a circuit or protect it from overload. Some circuits use ground as the termination point for the circuit, the final place where electricity arrives after it has done its work. Other circuits use ground as an alternate termination point where electricity will only arrive if it is not safe for electricity to pass through to its normal termination point. All electrical circuits have two poles of differing voltages. Not all circuits run to ground or connect to ground. A circuit can run from a pole with negative voltage to a pole with positive voltage, or it can run to an isolated zero-voltage pole without ever arriving at ground.

The term derives its name from the fact that the ground (the surface of the Earth) typically has near-zero voltage, and can absorb enough electricity that it can act as an effective termination point for almost any circuit.

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