7-Zip in Windows 7
|Initial release||18 July 1999|
|Discontinued||9.20 (November 18, 2010[±])|
|Operating system||Microsoft Windows, GNU/Linux, Mac OS X|
|Available in||79 languages, including Brazilian Portuguese, Czech, English, French, German, Italian, Japanese, Polish, Russian, Simplified Chinese, Sinhala, Spanish and Korean|
|License||GNU LGPLv2.1+ with unRAR restriction|
7-Zip is an open source file archiver. 7-Zip operates with the 7z archive format, but can read and write several other archive formats. The program can be used from a command line interface, graphical user interface, or with a window-based shell integration. 7-Zip began in 1999 and is actively developed by Igor Pavlov. The cross-platform version of the command line utility, p7zip, is also available.
The 7z archive format 
By default, 7-Zip creates 7z format archives with a
.7z file extension. Each archive can contain multiple directories and files. As a container format, security or size reduction are achieved using a stacked combination of filters. These can consist of pre-processors, compression algorithms, and encryption filters.
The core .7z compression uses a variety of algorithms, the most common of which are bzip2, LZMA2, and LZMA. Developed by Pavlov, LZMA is a relatively new system, making its debut as part of the 7z format. LZMA consists of a large LZ-based sliding dictionary up to 4 GB in size, backed by a range coder.
The official 7z file format specification is distributed with the program's source code, in the 'doc' subdirectory.
Other supported formats 
7-Zip supports a number of other compression and non-compression archive formats (both for packing and unpacking) including 7z, ZIP, GZip, bzip2, xz, tar and WIM. The utility also supports unpacking APM, ARJ, CHM, cpio, DEB, FLV, JAR, LHA/LZH, LZMA, MSLZ, onepkg, RAR, RPM, smzip, SWF, XAR and Z archives and CramFS, DMG, FAT, HFS, ISO, MBR, NTFS, SquashFS, UDF and VHD disk images.
7-Zip is able to open some MSI files, allowing access to the meta-files within along with the main contents. Some Microsoft CAB (LZX compression) and NSIS (LZMA) installer formats can be opened. Similarly, some Microsoft executable programs (.EXEs) which are self-extracting archives or otherwise contain archived content (e.g., some setup files) may be opened as archives.
When compressing ZIP or gzip files, 7-Zip uses its own DEFLATE encoder, which may achieve higher compression, but at lower speed, than the more common zlib DEFLATE implementation. The 7-Zip deflate encoder implementation is available separately as part of the AdvanceCOMP suite of tools.
The decompression engine for RAR archives was developed using source code of the unRAR program (which has a licensing restriction against creation of a RAR compressor).
Two command line versions are provided: 7z.exe, using external libraries; and a standalone executable 7za.exe containing built-in modules. However, 7za's compression/decompression support is limited to 7z, ZIP, gzip, bzip2, Z and tar formats. A 64-bit version is available, with support for large memory maps leading to faster compression. All versions support multi-threading.
The 7za.exe version of 7-Zip is available for Unix-like operating systems (including Linux, FreeBSD and Mac OS X), FreeDOS, OpenVMS and AmigaOS 4 under the name p7zip, also developed and maintained by Pavlov (7-zip).
- The 256-bit AES cipher. Encryption can be enabled for both files and the 7z directory structure. When the directory structure is encrypted, users are required to supply a password to see the filenames contained within the archive. WinZip-developed zip file AES encryption standard is also available in 7-Zip to encrypt ZIP archives with AES 256-bit, but it does not offer filename encryption as in 7z archives.
- Volumes of dynamically variable sizes, allowing use for backups on removable media such as writable CDs and DVDs.
- Usability as a basic orthodox file manager when used in 2-panel mode.
- Multiple-core CPU threading settings can be configured.
- The ability to attempt to open EXE files as archives, allowing the decompression of data from inside many "Setup" or "Installer" or "Extract" type programs without having to launch them.
- The ability to unpack archives with corrupted filenames, renaming the files as required.
- The ability to create self-extracting single- (but not multi-) volume archives.
- Command-line interface.
On TechRepublic, Justin James found the detailed settings for Windows File Manager integration were "appreciated," and called the compression/decompression benchmark utility "neat". And though the archive dialog has settings that "will confound most users", he concluded, "7-Zip fits a nice niche in between the built-in Windows capabilities and the features of the paid products, and it is able to handle a large variety of file formats in the process."
The 2011 review of version 9.20 in PC World magazine pointed out that 7-Zip can "compress and e-mail files in one easy step", and although it offers "options that most users should never have to think about ... The default settings are just fine."
See also 
- "HISTORY of the 7-Zip". www.7-zip.org. 2010-04-15. Archived from the original on 19 April 2010. Retrieved 2010-04-24.
- Pavlov, Igor (2012), 7-Zip, retrieved 2012-10-27
- Pavlov, Igor (2010). "7-Zip License for use and distribution". 7-zip.org. Archived from the original on 10 April 2010. Retrieved 2010-04-16.
- "P7ZIP". SourceForge.net. February 2009. Retrieved 2010-04-16.
- Pavlov, Igor. 7-zip. Retrieved 2012-10-31.
- Pavlov, Igor. License. 7-zip.org. Retrieved 2012-10-31.
- "SourceForge.net: 2007 Community Choice Awards". SourceForge.net. 2007. Archived from the original on 26 March 2010. Retrieved 2010-04-16.
- Diaz, Antonio Diaz. "Lzip". lzip.nongnu.org. Archived from the original on 29 July 2010. Retrieved 29 July 2010.
- 7z format. 7-zip.org.
- "AES Encryption Information: Encryption Specification AE-1 and AE-2". winzip.com. January 30, 2009, WinZip International LLC.
- "Command Line Syntax". sevenzip.sourceforge.jp.
- "7-Zip file compression tool". Snapfiles.com. WebAttack Inc. Retrieved 2012-10-12.
- James, Justin (November 10, 2009). "Review: 7-Zip file compression application". Tech Republic. pp. 1–2.
- Spector, Lincoln (March 15, 2011). "Editorial Review of 7-Zip (32-bit version)". PC World.
- "Compression Performance: 7-Zip, MagicRAR, WinRAR, WinZip". Tom's Hardware. Bestofmedia Group. 2013-03-19. p. And The Undisputed Winner Is...
|Wikimedia Commons has media related to: 7-Zip|
- Official website
- 7-Zip on SourceForge.net
- 7-Zip .NET wrapper
- 7-Zip Portable at PortableApps.com
- 7-Zip Theme Manager