An Original Equipment Manufacturer (OEM) is the organization responsible for the design, manufacture, sale and in some cases in-service support and recycling of a finished product. Boeing and Airbus are examples of OEMs in the aerospace sector; BMW and Ford are automotive examples.
OEMs purchase components and sub-assemblies for use in the final product, and may subcontract substantial amounts of design and manufacturing (for example, Apple is an OEM which performs very little manufacturing of Apple products).
OEMs oversee the product lifecycle from design to shipment for quality assurance. Sometimes, they also manage the lifecycle until end of life and provide tracking of equipment from as-designed, as-built, as-changed, as-shipped and as-serviced.