X Window System servers run on computers with bitmap displays.
The server distributes user input to and accepts output requests from various client programs through a variety of different interprocess communication channels.
Although the most common case is for the client programs to be running on the same machine as the server, clients can be run transparently from other machines (including machines with different architectures and operating systems) as well.
X supports overlapping hierarchical subwindows and text and graphics operations, on both monochrome and color displays.
The number of programs that use X is quite large. Programs provided in the core X.Org Foundation distribution include:
- a terminal emulator, xterm;
- a window manager, twm;
- a display manager, xdm;
- a console redirect program, xconsole;
- a mail interface, xmh;
- a bitmap editor, bitmap;
- resource listing/manipulation tools, appres, editres;
- access control programs, xauth, xhost, and iceauth;
- user preference setting programs, xrdb, xcmsdb, xset, xsetroot, xstdcmap, and xmodmap;
- clocks, xclock and oclock;
- a font displayer, xfd;
- utilities for listing information about fonts, windows, and displays, xlsfonts, xwininfo, xlsclients, xdpyinfo, xlsatoms, and xprop;
- screen image manipulation utilities, xwd, xwud, and xmag;
- a performance measurement utility, x11perf;
- a font compiler, bdftopcf;
- a font server and related utilities, xfs, fsinfo, fslsfonts, fstobdf;
- a display server and related utilities, Xserver, rgb, mkfontdir;
- a print server and related utilities, Xprt, xplsprinters;
- remote execution utilities, rstart and xon;
- a clipboard manager, xclipboard;
- keyboard description compiler and related utilities, xkbcomp, xkbprint, xkbbell, xkbevd, xkbvleds, and xkbwatch;
- a utility to terminate clients, xkill;
- an optimized X protocol proxy, lbxproxy;
- a firewall security proxy, xfwp;
- a proxy manager to control them, proxymngr;
- a utility to find proxies, xfindproxy;
- libxrx.so and libxrxnest.so;
- an RX MIME-type helper program, xrx; and
- a utility to cause part or all of the screen to be redrawn, xrefresh.
Many other utilities, window managers, games, toolkits are included as user-contributed software in the X.Org Foundation distribution, or are available using anonymous ftp on the Internet.