The device independent file format (DVI) is the output file format of the TeX typesetting program, designed by David R. Fuchs and implemented by Donald E. Knuth in 1982. Unlike the TeX markup files used to generate them, DVI files are not intended to be human-readable; they consist of binary data describing the visual layout of a document in a manner not reliant on any specific image format, display hardware or printer. DVI files are typically used as input to a second program (called a DVI driver) which translates DVI files to graphical data. For example, most TeX software packages include a program for previewing DVI files on a user's computer display; this program is a driver. Drivers are also used to convert from DVI to popular page description languages (e.g. PostScript, PDF) and for printing.