Piston .

Piston is a type of engine part that converts pressure into mechanical motion. It is used in internal combustion engines and other machines that require linear motion from pressure. A piston is made up of a cylindrical body, a head at one end, and a skirt at the other end. The head seals the cylinder and the skirt is connected to a connecting rod which is attached to a crank shaft. The piston moves back and forth in the cylinder, compressing and releasing air or fuel to create power.