1 A component of a software system that handles a specific aspect of processing. Engines thus form part, or possibly the whole, of an application's back end. For example, a database engine provides database services other parts of the system; a search engine provides searching services; and so on. Engines can be shared among several applications — for example, through the client/server model — and are often bought from a third-party specialist supplier.
2Another name for back end.