The language PostScript or ps has become a standard for sending text and graphics to printers. PostScript is a page-description language developed and licensed by Adobe Systems. It was specifically designed to communicate the description of a printable page to a raster-output device, such as a laser printer, and is responsible in part for the desktop publishing revolution.
PostScript laser printers contain a fairly powerful computer which compiles the ps files sent to it and then generates the raster or dot-matrix files sent to the laser printing engine. The powerful microprocessor, a high memory requirement, and the licensing fee for the PostScript language are all reasons for the added expense of a PostScript printer. For example, a typical low-end PostScript printer may have a Motorola 68000 processor and 2 MB of memory, which is equivalent to an Apple Macintosh computer.
The PostScript files produced by graphics programs, or text filters, are readable text files-at least in the sense that C or Fortran programs are readable. Although you may find them complicated and confusing, we encourage you to look at some to get an idea of the information they tell the printer. Most users create and print PostScript files without ever looking at the files themselves or knowing anything about the PostScript language. PostScript is meant to describe a page to a printer and does not have to be understood or even viewed by humans. PostScript files are recognized as such by the first line of text in the file containing the two characters %! and by the .ps suffix to the file name. All PostScript files begin with lines like these:
%!PS-Adobe-2.0 %%Creator: dvips Copyright 1986-91 Radical Eye Software %%Title: tch.dvi %%Pages: 6 1 %%BoundingBox: 0 0 612 792