Chapter 13 covered remote text-based login servers ( rlogind , Telnet, and SSH). These servers, in conjunction with appropriate client programs on other computers, allow users to log in and run text-based programs on a Linux computer. Because Linux (and UNIX more generally ) supports a wide range of text-based tools, such text-based remote access servers allow users to perform most types of tasks with Linux. Many users, though, are most comfortable with a graphical user interface (GUI) for running programs. By themselves , text-based login servers don't support full GUIs, so users can't run popular GUI programs like The GIMP, Netscape Navigator, or StarOffice. (A few programs, like Emacs, support both GUI and text-based operation.) In order to provide access to GUI tools, you need to run special GUI servers. The most common of these in Linux is the X Window System (or X for short), which is Linux's native GUI environment. X is inherently network-capable, so you only need appropriate X software on the remote system. In some cases, you can use text-based login tools as part of the process, but in other cases you may want to run a special X-based login tool. Another option is to use a package called Virtual Network Computing (VNC), which provides network GUI access similar to that of X, but using different protocols. This chapter covers all of these options.