Files are often compressed to save space. To use the files, you'll have to know how to extract them. First we look at the file command. This can tell you how a certain file is compressed.

The file command looks at a file and tells you what it is (text, mp3, zip, etc.)

On windows the most common type of compressed file is .zip . This both archives (makes all the files into one) and compresses (tries to make that one file smaller). Generally on UNIX systems the archiving and compressing are done separately. We'll look first at the archiving tool.