engine(A system component that provides complex capability and performs operations on objects); application(A Commerce Server application is a logical representation of an application in Microsoft Internet Information Services (IIS); it appears in both Commerce Server Manager and the IIS console trees. In the IIS console tree an application is either at the root directory level of the Web site or at a subdirectory level of the Web site); middleware(Software that sits between two or more types of software and translates information between them. Middleware can cover a broad spectrum of software and generally sits between an application and an operating system, a network operating system, or a database management system)
