The rise of the microprocessor-based server was facilitated by the development of several versions of the Unix operating system to run on the Intel microprocessor architecture, including Solaris, Linux and FreeBSD. The Microsoft Windows series of operating systems also now includes server versions that support multitasking and other features required for servers, beginning with Windows NT. The current Windows Server version is Windows Server 2003.

X Window server

The X Window System can cause some confusion in the definition of servers and clients. One might expect that the "server" in X would be the computer in which individual programs are running. In reality, an X server provides access to computer input and output devices, such as monitors, keyboards, and mice. Programs that are running in an X environment connect to the server to gain access to the hardware.

The X protocol is designed to operate over a network. The only requirement for a client to connect to a server is a network connection. In most situations however, the servers and clients run on the same physical machine. In this case, either UNIX local sockets or a loopback interface act as transparent media for network connections between client and server.