ZIP file format
The ZIP file format is the most widely-used compressed file format in the IBM PC world.
The format was designed by Phil Katz for PKZIP, and in the form now used (PKZIP 2 format) it uses his DEFLATE algorithm for compression.
History
The ZIP file format was originally created by Phil Katz, founder of PKWARE. Katz created the ZIP file format in response to a legal challenge by Software Enhancement Associates (SEA) over their ARC archiver.
SEA was the legal entity created by Thom Henderson, his wife Irene and her brother. SEA was not a large corporation. ARC was sold via shareware, mostly to users of electronic bulletin board systems so they could package and compress files for upload and/or so they could decompress and unpack files after download. ARC was distributed not only as the executable software, but also its C source code.
Katz had copied ARC and converted the compression routines from C to optimised assembler code, which made it much faster. SEA initially tried to license Katz's archiver, called PKARC, but Katz refused. SEA then sued Katz for copyright infringement and won.
During settlement, Katz still refused to license PKARC to SEA, instead agreeing to pay SEA's legal fees and stop selling PKARC. He then went on to create his own file format PKZIP, and the .ZIP format he designed was a much more efficient compression format than .ARC. Once PKZIP was released, many users abandoned PKARC because of its slower performance and because Katz had successfully convinced them that he was the "good guy" being unfairly treated by an evil corporation.
Today
Today, zip files use the file extension ".zip" and have the MIME media type application/zip.
Many software utilities other than PKZIP itself are now available to create, modify or open zip files, notably WinZip, PicoZip, Info-ZIP and WinRAR.
See also
External links
- PKWARE (http://www.pkware.com/)
- PicoZip (http://www.picozip.com/)
- 7-Zip (http://www.7-zip.org/) is an LGPL licensed utility that supports 7z, ZIP, CAB, RAR, ARJ, GZIP, BZIP2, TAR, CPIO, RPM and DEB.
- Ben Baker remembers Phil Katz (http://www.bbsdocumentary.com/research/CONTROVERSY/LAWSUITS/SEA/baker.html)
- Thom Henderson's opinion of Phil Katz (http://www.esva.net/~thom/philkatz.html)
- Technical specifications of the PKZIP file formats (http://www.info-zip.org/pub/infozip/doc/)
- Original specification for the first version of the format (http://groups.google.com/groups?selm=14480%40cup.portal.com)
- Info-ZIP project website (http://www.info-zip.org/pub/infozip/)
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