Term usage in information technology

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.

A server computer (often called server for short) is a computer system that has been designated for running a specific server application or applications. A computer that is designated for only one server application is often named for that application. For example, when Apache HTTP Server (software) is a company's web server, the computer running it is also called the web server. Server applications can be divided among server computers over an extreme range, depending upon the workload. Under light loading, every server application can run concurrently on a single computer. Under heavy loading, multiple server computers may be required for each application. Under medium loading, it is common to use one server computer per server application, in order to limit the amount of damage caused by failure of any single server computer or security breach of any single server application. Any server computer can also be used as a workstation, but it is avoided in practice, again to contain risk.

Server or server computer is also a designation for computer models intended for use running server applications, often under heavy workloads, unattended, for extended time. While any "workstation" computer can run server operating systems and server applications, a server computer usually has special features intended to make it more suitable. Distinctions often include faster processor and memory, more RAM, larger hard drives, higher reliability, redundant power supplies, redundant hard drives (RAID), compact size and shape, modular design (e.g., blade servers often used in server farms), rack or cabinet mountability, serial console redirection, etc.

The name server or server appliance also applies to network-connected computer appliances or "appliance hardware" that provides specific services onto the network. Though the appliance is a server computer, loaded with a server operating system and a server application, the user need not configure any of it. It is a black box that does a specific job. The simplest servers are most often sold as appliances, for example switches, routers, gateways, print servers, net modems.

A server is defined as a multi-user computer that provides a service (e.g. database access, file transfer, remote access) or resources (e.g. file space) over a network connection.