In order to decompress them, you need the Gnu gzip program. A Postscript file can be viewed as the output a computer sends to a laserprinter, captured in a file.
Postscript describes objects on a page mathematically, rather than using a rigid bitmap.
For this reason Postscript has become a standard format for storing documents in a system-independent fashion. While there are some graphic programs that can handle postscript files, the best way to view a postscript file is to use a specialized viewer such as Ghostview or GSview, or the slower but more general program Ghostscript. This is a possible alternative to using a postscript viewer. However, some cautions should be taken here. If the file has been processed by an email program or is being printed using a wordprocessor, then text or control codes may have been added before this line.