GNU Zip. A GNU open-source replacement for the 'compress' program.
Gzip is based on the 'deflate' algorithm, which is a combination of LZ77 and Huffman coding. 'Deflate' was developed in response to patents that covered LZW and other compression algorithms and limited the usability of 'compress' and other popular archivers.
In order to make it easier to develop software that uses compression, the Zlib library was created. It supports the Gzip file format and 'deflate' compression. The library is widely used, because of its small size, efficiency and versatility.