In a car with a manual transmission, the clutch is responsible for transferring power from the engine to the rear wheels. It's what helps the driver to shift gears while driving without causing harm to the transmission or engine. A clutch disk, also known as a friction disc, and a pressure plate make up the "clutch." The clutch disc is sandwiched between the pressure plate and an aluminum or steel flywheel.
The pressure plate squeezes the clutch disc against itself while a Mustang or any other rear-wheel-drive car is driving and in gear, and the flywheel then transfers engine power to the transmission. The power is then transferred from the transmission to the driveshaft, which then transfers it to the differential, and finally to the rear wheels. With the exception of the power leaving the transmission, the mechanism is the same in a front-wheel-drive vehicle. Instead of a driveshaft, the power leaves the transmission and travels through the axles to the front wheels.
When the clutch is engaged, power is constantly transferred to the rest of the drivetrain. To shift gears, however, the clutch pedal is depressed, causing the pressure plate's springs to compress, causing the clutch disk to release from the flywheel. This allows the engine to rotate independently of the transmission, allowing for proper gear changes. The clutch pedal is released after the transmission is moved into gear, allowing the pressure plate to compress the clutch disk to the flywheel once more, passing power back through the drivetrain.