Ghostscript is an open technology that has evolved over 10 years. It is a
fully functional PDF and PostScript LanguageLevel 3 interpreter. In recent
years Ghostscript has evolved into a very general graphics engine with
several interpreter front ends (PostScript, PDF, Hewlett-Packard PCL 5 and
PCL XL) and many graphics file formats and device drivers on the back end
(TIFF, JPEG, EPS, etc).
Ghostscript was developed from the beginning to be cross-platform, and currently runs in a very large number of environments, including many UNIX variants, Microsoft Windows, Macintosh, VMS, and others. Several "viewers" based on the Ghostscript technology have been developed for various platforms (such as Ghostview and gv for Unix and VMS, and GSview for Microsoft Windows and OS/2), and are available as pre-built applications for those platforms.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.