An OEM (original equipment manufacturer) is a company that uses product components from one or more other companies to build a product that it sells under its own company name and brand. (The term is sometimes mistakenly used to refer to the company that supplies the components.) IBM is an example of a supplier to the OEM market (and IBM is also an OEM itself since it uses other companies' parts in some of its products).

Many computer hardware manufacturers that have their own brand-name products derive considerable revenue by reselling the product or key parts of it to OEM companies that seem to be competing in the same market. Arguments for selling to an OEM are that you may be able to make money from a market sector that your competitor already owns (perhaps because they have an existing customer base) and that you can be a more efficient producer because you sell and manufacture more of your product. Frequently, an OEM company differentiates itself from the company it buys parts from by adding features or using different selling concepts. Many OEM companies are selling a "solution" tailored to a particular vertical market.