A switch is an electrical component that can make or break an electrical circuit.
The most common switch is a manually-operated device with one or more sets of contacts connected to external circuits. Closing the contacts will complete the circuit and allow electricity to flow between them, opening the contacts separates them and interrupts the current. This familiar mechanism is typically used to turn lights, machinery and equipment on or off.
Switches come in a wide variety of types, with different mechanisms and methods of actuation. Switches can maintained (toggles, rockers) or momentary (pushbuttons), can be operated by different variables (temperature, flow, current, voltage, etc.), and can have different contact variations (single-pole, double-pole double-throw, etc.).