On a machine running several X servers, programs identify the different instances of the X11 server by a display name like :1. The display name consists of three parts: the hostname, the display number, and the screen number. The hostname is the name of the machine where the X server runs. The display number is a unique identifier that distinguishes different X server instances on the same machine. The screen number is used to address different physical screens that are managed by the same X server instance. The display name has the format hostname:displaynumber.screennumber. If the hostname is omitted, it means the local machine. The screen number is also optional and defaults to 0. For example, :1 means the second X server instance on the local machine, screen 0. remote:0.1 means the first X server instance on the remote machine, screen 1. The display name is part of the topic 106.1: Install and configure X11, which is one of the objectives of the LPI Linux Administrator - 102 exam12. Reference: 1: LPI Linux Administrator - 102 (LPIC-1) 2: Exam 102 Objectives