GNU TeXmacs is a free scientific text editor, which was inspired by both TeX and GNU Emacs. The editor allows you to write structured documents via a &quot;wysiwyg&quot; and user friendly interface. The program implements high quality typesetting algorithms and TeX fonts. It is also possible to use TeXmacs as an interface to computer algebra systems. Finally, TeXmacs supports the Guile/Scheme extension language, which makes it possible to adapt the user interface to specific needs, and even to extend the editor.