XEmacs is a highly customizable open source text editor and application development system. It is protected under the GNU General Public License and related to other versions of Emacs, in particular GNU Emacs. Its emphasis is on modern graphical user interface support and an open software development model, similar to Linux. The XEmacs packages collection contains a large collection of useful lisp packages for XEmacs including mail readers, programming modes and utilities, and packages related to using XEmacs in multi-lingual environments.