What is the purpose of a clutch in a manual transmission vehicle?

The clutch connects and disconnects the engine from the transmission, allowing gear changes and vehicle launch from standstill. It consists of a friction disc pressed against the flywheel by a pressure plate. When the clutch pedal is pressed, the disc separates allowing gear changes; when released, friction engages the disc to transfer power. The clutch also provides slip during launch to prevent engine stall.