7 Zip

7-Zip is an open source file archiver for the Microsoft Windows operating system. It operates either as a command line program or with a graphical user interface. It also features integration with the Windows shell environment. Is free software, distributed under the GNU LGPL license. Features: High compression ratio in new 7z format with LZMA compression. For ZIP and GZIP formats 7-Zip provides compression ratio that is 2-10 % better than ratio provided by PKZip and WinZip.Self-extracting capability for 7z format.Integration with Windows Shell. Powerful command line version .Plugin for FAR Manager.

Other features:
>Powerful command line version
>High compression ratio in new 7z format with LZMA compression
>Strong AES-256 encryp
tion in 7z and ZIP formats
>Plugin for FAR Manager >Supported formats:
1. Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR
2. Unpacking only: ARJ, CAB, CHM, CPIO, DEB, DMG, HFS, ISO, LZH, LZMA, MSI, NSIS, RAR, RPM, UDF, WIM, XAR and Z.
>Self-extracting capability for 7z format
>Integration with Windows Shell
>Powerful File Manager
>For ZIP and GZIP formats, 7-Zip provides a compression ratio that is 2-10 % better than the ratio provided by PKZip and WinZip
>Localizations for 74 languages

Is a very simple compression software.The installation process is very simple and fast.A minus is because do not tell you when the setup is finished .It was created by Igor Pavlov and is competing with WinAce.Has a high compression ratio and archive files with .zip , .tar , .Gzip, .bZip2 and .7z (7-Zip) extensions.
Options are:
-Add (create archives)
-Extract
-Test
-Copy
-Move
-Delete
-Info
How do you make an archive with this software ?
Check Add button and than:
- type the name for archive and set the path
- set the compression level (store,fastest,fast,normal,maximum or ultra)
- choose compression method between LZMA,PPMd and BZip2
- set the dictionary size (in megabytes)
- set the font size (is a useful feature)
- select the number of CPU threads between 1 and 2;shows you the compressing and decompressing memory usage.
- set the update mode (add and replace ,update and add,synchronize files). You can create a SFX archive or compress shared files .
- choose a password for the new 7-Zip archive and set other parameters.

How extract files from archives ?
Select Extract function,choose the path and overwrite mode(overwrite without prompt,ask before,skip or auto rename files with the same name).If the archive was encrypted,you must type the password.

The Testing option work in this way:choose the archive and than press test.7-Zip show you the number of archives,the numbers or folders and files,the size(in kb or MB) and if there are errors.You can associate with following extensions:arj,bz2, bzip2,cab,gzip,iso,zip,tar,taz ,wim,tbz2 etc. Have plug-in options for system and folders.
Is available in more than 20 languages.Have benchmark option were show you the compression speed,CPU usage,elapsed time ,size and number of CPU threads .7z.exe is the command line version of this program and uses 7z.dll from the package;it is used by file manager also.
A help manual can be read pressing F1 key.7z is the extension who we recommend for archiving files because the compress ratio is good with 30 percent the other extensions(when you are using his tool).WinZip 10.0 beta,CABARC 5.1 and WinRAR 3.50 can compress ,but they not have better ratio than zip7 .
Is an open source software and can be downloaded for free;the unRar code is under license restrictions , but you can check this in detail on the producer site.