In general, a piston helps change fluid pressure to mechanical energy or vice versa. It provides a moving "stopper" within a cylinder to permit the compression of the fluid without leaks. The piston in an air compressor (for those kinds that have them) takes the mechanical energy applied to the crank shaft and uses it to compress the fluid (air) that it was designed to compress. Just the opposite is true for the piston in an internal combustion engine. The heated gases (fluids) in the compustion chamber force the piston down on the power stroke and transfer mechanical energy through the connecting rod into the crankshaft. Certainly more examples could be found using a variety of fluids.
Pistons, or rams, in hydraulic equipment take "fluid power" and use it to move, lift, crush or otherwise get tough with stuff on the business end of the ram. Compressed air (a fluid) is used to compress a piston to compress a hydraulic fluid to force a ram (long piston) up to lift the end of vehicle up into the air for a brake job or other undercarriage inspection or repair. This is a common air over hydraulic system on a large, mobile jack. There are more examples, but we'll put the (hydraulic) brakes on here and refer you to a link below that you can use for more information.
One of the parts in the piston are the piston head,
A bent engine piston is a reference to the piston rod. The piston cannot be bent, but the piston rod can be bent.
The driving force action on the piston is called piston effort.In other words the net resultant of all the other forces acting on the piston is called piston effort.
The piston rings create a seal between the piston and the cylinder wall.
There is the penis, the testicles, the scrotum, the prostate, the sperm duct etc.
A piston seal is a gasket designed to keep fluid from leaking around the piston. Piston seals are commonly used in brake calipers.
The piston doesn't twist it's way out. There is a ratchet screw adjustment that takes up the slack behind the piston. Screwing the piston back in resets the adjustment.
It is a spring metal sleeve that goes over a piston to compress the rings so that the piston can be install in the motor. It tightens down on the piston, forcing the rings into the grooves in the piston then you tap it into the cylinder.
It connects the piston to whatever the design calls for the piston to push or pull on. In a combustion engine, the piston rod connects the piston to the crankshaft, turning linear reciprocating motion into rotary motion.
A larger piston skirt to cylinder wall contact raises piston cooling. With turbo motors, they have piston oilers, they spray oil on the underside of the pistons, cooling the piston /crown.
That is the "stroke" of the piston.
No a Piston is not a breed of horse.