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ZIP files

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Filename extension: .zip, .zipx (newer compression algorithms)
Internet media type: application/zip
Uniform Type Identifier: com.pkware.zip-archive
Magic number: none, though PK\\003\\004 , PK\\005\\006 (empty archive), or PK\\007\\008 (spanned archive) are common.
Developed by: Phil Katz, PKWARE
Initial release: 1989
Latest release: 6.3.3 / 1 September 2012
Type of format: Data compression
Extended to: JAR (EAR, RAR (Java), WAR), Office Open XML (Microsoft), Open Packaging Conventions, OpenDocument (ODF), XPI (Mozilla extensions)
Standard: APPNOTE from PKWARE

ZIP is a file format for archiving (using a single file to store multiple files) and data compression (decreased employed space in the digital media space) without loss of quality. We can therefore compare the combination of tar (archiving) and gzip (compression) through a compressed .tgz archive.

JAR (Java Archive), ODT ( OpenDocument) and Open XML ( OOXML) formats, are based on the ZIP format.

ZIP64 format was introduced by PKWARE in version 4.5 of the ZIP specification to circumvent the limitation of file size of 4 GB of the initial specification.

The zip file format can cause interoperability problems in file names containing characters other than Latin characters without accents, especially when different Windows -Linux platforms are used and / or in areas using different localization settings.

Decompression programs

Microsoft Windows operating system, from Me version, can handle Zip files seamlessly via the “Compressed Folder” function.

A large number of programs know to perform compression and decompression of files as standalone programs integrating into a file manager, under all operating systems.

The market leader has long been Winzip (shareware), but many multiformat software, often free, like PeaZip and 7-Zip, know how to operate, both reading and writing.

Using zip as an interchange format between OS is not always recommended, especially if the different environments do not use the same character encoding for file names (it is preferred the 7z format in this case).

Being able to extract the files by unzipping program does not preclude the possibility to read the contents, which requires the provision of a program of file type.

Tips

In the case of OpenOffice.org / LibreOffice office software, it contains its own unzipper, making operationsof  unpacking / decompression and reverse completely transparent. In case you would like to study the contents of an ODF document just change the extension to .zip (Microsoft Windows), and unzip it with any unzip tool. This is a simple way to recover, for example, the images in a text document.

Translated and adapted from Wikipedia under GNU Free Documentation License.

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