Xdvi allows you to preview the TeX text formatting system's output .dvi files on an X Window System.

If you are installing tetex and you use PlainTeX or you are using DVI files, you will also need to install tetex-xdvi which allows you to view DVI files. Consider installing tetex-dvips (for converting .dvi files to PostScript format for printing on PostScript printers), and tetex-latex (a higher level formatting package which provides an easier-to-use interface for TeX). If you are not a TeX expert, you will probably also want to install the tetex-doc package, which contains documentation for the TeX text formatting system.