The X Window System, commonly referred to as X, is a network-based graphical window system. The X Window System uses a client-server architecture. It enables multiple programs to share and access a common set of hardware. This hardware includes both input and display devices such as mouse, keyboards, video adapters, and monitors that are connected to the server.
The X Window System consists of X server and X clients. The X clients are application programs that do not have direct access to the display. They communicate with the X server which renders the display.
The X architecture allows clients and servers to work on the same system or on different systems with different architectures. The X architecture defines a stream protocol for clients-server communication. This protocol can be exposed over a network to allow clients to connect to a server on a different machine. Therefore, you can set up your system so that the X server is running on the laptop in front of you, and the display is generated by an X client that is running in a remote system.