A clutch is a mechanical device used in vehicles and machinery to engage and disengage power transmission, particularly between the engine and the transmission. Its primary function is to enable smooth starting, stopping, and shifting of gears without stopping the engine. Clutches are essential components in both manual and automatic transmissions.

Modern vehicles often have safety features like a clutch interlock switch, ensuring that the engine cannot start unless the clutch pedal is depressed (in manual transmissions).