RAR is a proprietary archive file format that supports

data compression In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compress ...

, 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 extension A filename extension, file name extension or file extension is a suffix to the name of a computer file (e.g., .txt, .docx, .md). The extension indicates a characteristic of the file contents or its intended use. A filename extension is typically ...

s used by RAR are .rar for the data volume set and .rev 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 .rar, then .r00 for the second, and then .r01, .r02, 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, owns the copyright. Version 3 of RAR is based on Lempel-Ziv ( LZSS) and

prediction by partial matching Prediction by partial matching (PPM) is an adaptive statistical data compression technique based on context modeling and prediction. PPM models use a set of previous symbols in the uncompressed symbol stream to predict the next symbol in the st ...

(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 about 9,000 PB.

Versions

The RAR file format revision history: * 1.3 – the first public version, does not have the "Rar!" signature. * 1.5 – changes are not known. * 2.0 – released with WinRAR 2.0 and Rar for MS-DOS 2.0; features the following changes: ** Multimedia compression for true color bitmap images and uncompressed audio. ** Up to 1 MB compression dictionary. ** Introduces archives data recovery protection record. * 2.9WinRAR 5.0 and RAR for Android refer to this format as RAR4. – released in WinRAR version 3.00. Feature changes in this version include: ** File extensions is changed from ''.rar, .r00, .r01, etc.'' to ''.part001.rar, .part002.rar, etc.'' ** Encryption of both file data and file headers. ** Improves compression algorithm using 4 MB dictionary size, Dmitry Shkarin's PPMII algorithm for file data. ** Optional creation of "recovery volumes" (.rev files) for error correction, which can be used to reconstruct missing files in a volume set. ** Support for archive files larger than 9 GB. ** Support for

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...

file names stored in

UTF-16 UTF-16 ( 16-bit Unicode Transformation Format) is a character encoding capable of encoding all 1,112,064 valid code points of Unicode (in fact this number of code points is dictated by the design of UTF-16). The encoding is variable-length, as c ...

little endian format. * 5.0 – supported by WinRAR 5.0 and later. Changes in this version: ** Maximum compression dictionary size increased to 1 GB (default for WinRAR 5.x is 32 MB and 4 MB for WinRAR 4.x). ** Maximum path length for files in RAR and ZIP archives is increased up to 2048 characters. ** Support for

file names stored in

UTF-8 UTF-8 is a variable-length character encoding used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode'' (or ''Universal Coded Character Set'') ''Transformation Format 8-bit''. UTF-8 is capable of ...

format. ** Faster compression and decompression. ** Multicore decompression support. ** Greatly improves recovery. ** Optional AES encryption increased from 128-bit to 256-bit. ** Optional 256-bit BLAKE2 file hash instead of a default 32-bit

CRC32 A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to digital data. Blocks of data entering these systems get a short ''check value'' attached, based on ...

file checksum. ** Optional duplicate file detection. ** Optional

NTFS New Technology File System (NTFS) is a proprietary journaling file system developed by Microsoft. Starting with Windows NT 3.1, it is the default file system of the Windows NT family. It superseded File Allocation Table (FAT) as the preferred fi ...

hard and symbolic links. ** Optional Quick Open Record. Rar4 archives had to be parsed before opening as file names were spread throughout the archive, slowing operation particularly with slower devices such as optical drives, and reducing the integrity of damaged archives. Rar5 can optionally create a "quick open record", a special archive block at the end of the file that contains the names of files included, allowing archives to be opened faster. ** Removes specialized compression algorithms for Itanium executables, text, raw audio (WAV), and raw image (BMP) files; consequently some files of these types compress better in the older RAR (4) format with these options enabled than in RAR5. ;Notes

Software

Operating system support

Software is available for Microsoft Windows (named WinRAR),

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, wh ...

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

, and Android; archive extraction is supported natively in

ChromeOS ChromeOS, sometimes stylized as chromeOS and formerly styled as Chrome OS, is a Linux-based operating system designed by Google. It is derived from the open-source ChromiumOS and uses the Google Chrome web browser as its principal user interf ...

. WinRAR supports the Windows

graphical user interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, in ...

(GUI); other versions named RAR run as console commands. Later versions are not compatible with some older operating systems previously supported: * WinRAR v6.10 supports

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...

and later. * WinRAR v6.02 is the last version that supports

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Windows 2000 for high-end and ...

.WinRAR Release History; RARsoft.
/ref> * WinRAR v4.11 is the last version that supports

Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft and oriented towards businesses. It was the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and was official ...

. * WinRAR v3.93 is the last version that supports

Windows 95 Windows 95 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of operating systems. The first operating system in the 9x family, it is the successor to Windows 3.1x, and was released to manufactur ...

, 98, ME, and NT 4.0. * WinRAR 2.06 is the last version to support Windows 3.1, Windows NT 3.1, Windows NT 3.5, Windows NT 3.51 and Win32s. * RAR v3.93 is the last version that supports

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few op ...

and

OS/2 OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 ...

on 32-bit

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was ...

CPUs such as

80386 The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistorsRSX DPMI extender. * RAR v2.50 is the last version that supports MS-DOS and OS/2 on 16-bit x86 CPUs such as

Intel 8086 The 8086 (also called iAPX 86) is a 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-bit data bus (al ...

8088 The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers ...

, and

80286 The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non- multiplexed address and data buses and also the f ...

Creating RAR files

RAR files can be created only with commercial software WinRAR (Windows), RAR for Android,

command-line A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...

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. * RARLAB distributes the C++ source code and binaries for a command-line unrar program. The license permits its use to produce software capable of unpacking, but not creating, RAR archives, without having to pay a fee. It is not a

free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, ...

license. *

7-Zip 7-Zip is a free and open-source file archiver, a utility used to place groups of files within compressed containers known as "archives". It is developed by Igor Pavlov and was first released in 1999. 7-Zip has its own archive format called 7z ...

, a

free and open-source Free and open-source software (FOSS) is a term used to refer to groups of software consisting of both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the source ...

program, starting from 7-Zip version 15.06 beta can unpack RAR5 archives, using the RARLAB unrar code. * PeaZip is a free RAR unarchiver, licensed under the

LGPL The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

, it runs as a RAR extractor on Linux, macOS, and Windows, with a GUI. PeaZip supports both pre-RAR5 .rar files, and files in the new RAR5 format. * The Unarchiver is a proprietary software unarchiver for RAR and other formats. It runs on macOS, and the command-line version, , also runs on Windows and on Linux, and is

licensed under the

. It supports all versions of the RAR archive format, including RAR3 and RAR5.The Unarchiver Website
contains unar. Accessed 5 February 2013. * UNRARLIB (UniquE RAR File Library) was an obsolete free software unarchiving library called "unrarlib", licensed under the GPL. It could only decompress archives created by RAR versions prior to 2.9; archives created by RAR 2.9 and later use different formats not supported by this library. The original development-team ended work on this library in 2007. * libarchive, a free and open source library for reading and writing a variety of archive formats, supports all RAR versions including RAR5. The code was written from scratch using RAR's "technote.txt" format description.

Other uses of ''rar''

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

References

External links

*
RARLAB FTP download website
current and old versions of WinRAR and RAR

{{DEFAULTSORT:Rar Computer-related introductions in 1993 Archive formats Russian inventions