ZIP

Zip is an archive format for storing one or more files which have been compressed.

Text based files may be significantly compressed using the zip compression, but image files will usually exprience little or no compression.

Zip came from PKZIP, which was originally developed by Phil Katz, who created algorythms for compressing files. PKZIP, PKUNZIP were the formats for this.

The Zip/UnZip algorithms are now in the public domain.

You may also see .gz extensions, which is another form of .zip derivative, but can produce even smaller archives, and also degrees of compression. For more on that, see Gzip.