RAR is a proprietary archive file format that supports data compression, error correction and file spanning. It was developed in 1993 by Russian software engineer Eugene Roshal and the software is licensed by win.rar GmbH. The name RAR stands for Roshal Archive.

File format

The filename extensions used by RAR are for the data volume set and for the recovery volume set. Previous versions of RAR split large archives into several smaller files, creating a "multi-volume archive". Numbers were used in the file extensions of the smaller files to keep them in the proper sequence. The first file used the extension, then for the second, and then , , etc. RAR compression applications and libraries (including GUI based WinRAR application for Windows, console rar utility for different OSes and others) are proprietary software, to which Alexander L. Roshal, the elder brother of Eugene Roshal, holds the copyright. Version 3 of RAR is based on Lempel-Ziv (LZSS) and prediction by partial matching (PPM) compression, specifically the PPMd implementation of PPMII by Dmitry Shkarin. The minimum size of a RAR file is 20 bytes. The maximum size of a RAR file is 9,223,372,036,854,775,807 (263−1) bytes, which is one byte less than 8 EiB.

Versions

The RAR file format revision history:

Software

Operating system support

Software is available for Microsoft Windows (named WinRAR), Linux, FreeBSD, macOS, and Android; archive extraction is supported natively in ChromeOS. WinRAR supports the Windows graphical user interface (GUI); other versions named RAR run as console commands. Later versions are not compatible with some older operating systems previously supported:

Creating RAR files

RAR files can only be archived with the proprietary WinRAR (Windows), RAR for Android, command-line RAR (Windows, MS-DOS, macOS, Linux, and FreeBSD), and other software that has written permission from Alexander Roshal or uses copyrighted code under license from Roshal. The software license agreements forbid reverse engineering.

Third-party software for extracting RAR files

Several programs can unpack the file format.

Other uses of rar

The filename extension rar is also used by the unrelated Resource Adapter aRchive file format.