An X terminal is a device which communicates and displays over a network using a distributed network window system known as X. Typically, the terminal's X software, known as the X server, is retrieved from the network at boot time. Programs other then the X server software are not run locally on the X terminal (with some exceptions); instead, the X terminal displays programs running on other hosts on the network. The X terminal, therefore, is a type of network computer which uses the X protocol to access network resources.
The NCD X terminal (model Xncd19r was used in preparation of this document) has an RJ-45 (twisted pair) connector for use with 10baseT Ethernet. A hub is required to link more than two Ethernet devices using twisted pair. If the X terminal and its host are the only devices in the network, they may be connected with a 'null' cable which is described in the Linux Ethernet HOWTO document.
The terminal's X server software file is available from the manufacturer and presumably is provided with the terminal upon initial purchase. This file will reside on the boot host where it can be accessed by the X terminal when it boots. This file is specific to the terminal type but independent of boot host. The terminal can boot from any host which supports the boot communication protocol (explained later). In addition to X server, the X software may also include applications, like a window manager, which can run locally on the X terminal itself.