Aftermarket auto parts are any parts for a vehicle that are not produced by the car's maker, according to Edmunds.com. This can include parts that directly replace a broken or worn out part or parts that are designed for performance enhancement.
Parts used for direct replacement do not void a car's warranty; however, some aftermarket parts do not come with a warranty, notes Edmuds.com. Aftermarket parts are generally less expensive than original equipment manufacturer parts, but customers need to be careful if the price seems too good to be true. Aftermarket parts may also be a higher quality and offer more variety than original equipment manufacturer parts.