Server used as an adjective, as in server operating system, refers to the products ability to handle multiple requests, and is said to be server-grade. A server operating system is intended or better enabled to run server applications. The differences between the server and workstation versions of a product can vary from the removal of an arbitrary software limits due to licensing, as in the case of Windows 2000, or the addition of bundled applications as in Mac OS X Server.A server is a computer program that provides services to other computer programs and their users, in the same or other computer. The physical computer that runs a server program is also often referred to as server.
Services can be supplied centrally by the use of a server; in other cases all the machines on a network have the same status with no dedicated server, and services are supplied peer-to-peer.