X Files

.xstart: Your .xstart file is used by X Windows when X is started. It contains key bindings for X applications and loads the contents of the .Xdefaults file for setting the properties of applications.
.Xdefaults: Your .Xdefaults file contains properties for different X application windows. The properties include window size, window colors, font size and style, icon, etc.
.Xsessions: Your .Xsession file contains the applications that are started when you log onto an Xterm. This file also contains an entry for starting the window manager for an Xterm.
.xtools: Your .xtools file contains the applications that are started when you start X Windows. This file also contains an entry for starting the window manager. By default, the window manager is twm .