A crankshaft is a mechanical component that converts linear piston motion into rotational engine power. It consists of a series of links or rods connected by joints, with each rod having one end attached to the piston and the other end connected to the flywheel or another part of the engine through a connecting rod. The crankshaft is responsible for converting the linear motion of the pistons into rotational movement, which powers the vehicle's wheels in an internal combustion engine.