Open RAR File

ZIP File

ZIP is a compression file format created in 1989 by Phil Katz. ZIP is an open format and doesn’t require a license to be implemented and fully supported in the developer app. First compression and decompression utility with ZIP support was PKZIP. PKZIP was developed by Phil Katz and was sold through PKWARE company. PK stands for Phil Katz initials. PKZIP was distributed as a shareware with a license fee of $25 (or $47 with manual). The file format of ZIP was fully documented in APPNOTE.TXT file distributed with PKZIP. This and the fact that Phil Katz declared that ZIP file format will always be free allowed ZIP to become a predominant compression file format replacing previous leader ARC.

ZIP file format uses DEFLATE method of compression. DEFLATE is a combination of LZ77 algorithm and Huffman coding. LZ77 algorithm uses a sliding window compression and Huffman coding is used to further reduce size of compressed stream.

Certain apps which can open ZIP files may charge money for their licenses but there are number of free software packages on the market with full ZIP format support. Below are most popular applications which support ZIP file format:

• Microsoft Windows OS can natively create and open ZIP files. To compress you just need to select files you need to compress, right-click on them and select “Send to…”, and then select “Compressed (Zipped) folder”. For more details visit "Windows compress/uncompress help page"
• Apple Mac OS can also natively create and open ZIP files. To compress you need to select files you need to compress in Finder, right-click on them and select “Compress” from the pop-up menu. To decompress just double-click on compressed file and it will extract to the current folder.
• WinZip is a free to try software which supports ZIP and many other compression formats. Also advanced features like secure archive and multi-volume archives are supported.

There is a version of ZIP file format called ZIPX which allows more advanced compression methods like BZip, LZMA, PPMd, Jpeg and Wavpack to be used. ZIP files are transferred over e-mail or internet using application/zip multipurpose internet mail extensions (MIME) type.