.ZIP is an archive file format that supports lossless data compression. A .ZIP file may contain one or more files or folders that may have been compressed. The .ZIP file format permits a number of compression algorithms. The format was originally created in 1989 by Phil Katz, and was first implemented in PKWARE, Inc.'s PKZIP utility, as a replacement for the previous ARC compression format by Thom Henderson. The .ZIP format is now supported by many software utilities other than PKZIP. Microsoft has included built-in .ZIP support (under the name "compressed folders") in versions of Microsoft Windows since 1998. Apple has included built-in .ZIP support in Mac OS X 10.3 (via BOMArchiveHelper, now Archive Utility) and later. Most free operating systems have built in support for .ZIP in similar manners to Windows and Mac OS X.
Bzip2 is a free program developed under BSD license that compresses and decompresses files using compression algorithms Burrows-Wheeler and Huffman coding. The compression ratio achieved depends on the contents of the file to be compressed, but usually is far better to compressor based on the algorithm LZ77 / LZ78 (gzip, compress, WinZip, PKZip, ...). In return, bzip2 uses more memory and execution time.