Server has several related meanings.

    In information technology, a server (also called a server application) is "an application program that accepts connections in order to service requests by sending back responses." (RFC 2616 (Hypertext Transfer Protocol -- HTTP/1.1)) A server application can run on the same computer as the client application using it, or they can connect through a computer network. Examples include file server, database server, backup server, print server, mail server, web server, FTP server, application server, VPN server, DHCP server, DNS server, WINS server, logon server, security server, domain controller, backup domain controller, proxy server, firewall, etc.

Server is an adjective in the term server operating system. A server operating system is intended, enabled, or better able to run server applications. The differences between the server version and the "workstation" version of an operating system vary. Sometimes (as in the case of Windows 2000 and Windows 2000 Server), the primary difference is the removal of arbitrary license-dependent limits on the number of network file share connections accepted. Some server editions include additional server applications bundled with the operating system. Some server applications (e.g. Microsoft IIS) impose arbitrary limits on the number of HTTP connections they will accept, depending on whether they are running under a server operating system or not.