Piston rings are essential components in an internal combustion engine. They are circular metal rings that fit into grooves on the outer surface of a piston. Their primary function is to create a seal between the piston and the cylinder wall, preventing the escape of combustion gases and maintaining engine efficiency. There are typically three types of piston rings: compression rings, oil control rings, and scraper rings. The compression rings help seal the combustion chamber, while the oil control rings manage the oil consumption by scraping excess oil off the cylinder walls. Proper functioning of piston rings is crucial for optimal engine performance and longevity.