At some point, you may have been told by a car shop that they had an OEM part in stock to use for your repairs. OEM parts are those produced by the same manufacturer. They produce the genuine car parts used at your car dealership. Most automakers don't actually manufacture the parts used in-house in their vehicles. Independent companies produce these parts, which are then labeled by the car company with their logo and specific packaging. Whoever the manufacturer, these parts have generally been carefully inspected to ensure that they meet quality regulations. You can find both new and recycled OEM parts at car repair shops.

By contrast, aftermarket parts are those which have been produced by manufacturers other than the company that created the original part for the car company. Aftermarket parts are intended to offer the same performance and fit as the OEM part. The companies that manufacture them have purchased the rights to create and distribute the parts. These parts have generally been manufactured using different machinery than their OEM counterparts, and as a result, may have a somewhat different looks and feel. There are even companies that choose to redesign the parts once they have acquired the rights, either because they feel they can improve upon the original or because they are looking for a way to reduce the cost of manufacturing the parts. While this means that sometimes you can get a superior part for a lower price, it also means that there may be times that purchasing an aftermarket product means that you will be installing an inferior part in your automobile. Unfortunately, aftermarket parts are not always produced under the same guidelines and don't always undergo the same level of inspection.

In the end, your goal is to purchase a part that reliably performs the function for which it was designed. It is your choice as the car owner that determines what type of part is installed in your car. It is important to learn as much as you can about your options so that you will make an informed decision that results in the peace of mind you want.