The X server manages X clients, but the relationship is reversed compared to traditional client-server model applications. Each local machine contains the X server, and the X clients are run on the remote machines, but may also run in the same local machine as the X server.

In traditional client-server implementations, the user of the client requests data from the server, which then displays them on the user's screen through the client. In the case of the X system, however, the user controls the server in order to control clients residing in remote workstations so that multiple clients can be controlled at once, providing the user with different applications that are running in different machines. In this way, more tasks can be done without slowing down the user's machine.

The X server provides the following basic types of services:

• Input handling
• Window services
• Graphics
• Text and fonts
• Resource management