File archiving is used to collect multiple files together into a single file for easier portability, storage, or sharing. Archiving is also used to compress files in order to save disk space or for faster uploading.
Archiving is often used to package software for distribution, since software programs generally include several files, including documentation. The archive is known as a package.
A file archiver is a computer application that combines these files together into one archive file or, in some cases, a series of archive files. File archivers often use lossless data compression in order to reduce the size of the archive. For a proper reconstruction of the archived files to take place, the archiver stores metadata, or at least the names and lengths of the original files, while many archivers store additional metadata, including the original timestamps, file attributes, and access control files. The process of producing an archive file is called archiving or packing, while the process of reconstructing the original files from the archive is known as unarchiving, unpacking, or extracting.
Data compression is the process of encoding information so that the resulting file uses fewer bits than the original file. As used by a file archiver, the resulting file will usually be smaller than the sum of the individual files that it contains.
File compression can be lossy or lossless. Lossy compression reduces the number of bits by removing unnecessary or less important information. In the case of image files, some loss of information may be acceptable, but there is a tradeoff between preserving information and reducing the size of the file, as the loss of data is not reversible. This is not as likely to be acceptable when it comes to archiving computer software programs.
Lossless data compression algorithms use statistical redundancy to represent data without loss of information so that the process is reversible. There are several schemes to reduce file size, largely by eliminating redundancy.
Archive formats used for archiving only include A, AR, CPIO, ISO, LBR, MAR, SBX, SHAR, and TAR.
Those used for compression only include ?XF, BZ2, F, GZ, LZ, LZMA, LZO, RZ, SFARK, SZ, ?Q?, ?Z?, YZ, Z, and ??_.
Archive formats used for both archiving and compression are 7Z, ACE, AFA, ALZ, APK, ARC, ARJ, B1, B6Z, BA, BH, CAB, CAR, CDX, CFS, CPT, DAR, DD, DGC, DMG, EAR, GCA, HA, HKI, ICE, JAR, KGB, LHA, LZH, LZX, PAK, PARTIMG, PAQ6, PAQ7, PAQ8, PEA, PIM, PIT, QDA, RAR, RK, S7Z, SDA, SEA, SEN, SFX, SHK, SIT, SITX, SQX, TAR.BZ2, TAR.GZ, TAR.IZ, TAR.XZ, TAR.Z, TBZ2, TGZ, TIZ, TYZ, UC, UCA, UC0, UC2, UCN, UE2, UHA, UR2, WAR, WIM, XAR, XP3, YZ1, ZIP, ZIPX, ZOO, ZPAQ, and ZZ.
One of the most common file formats for archiving is ZIP. Around since 1989, ZIP was first implemented in PKWARE's PKZIP utility, as a replacement for the ARC compression format, and has quickly been supported by several other utilities and software companies, including Microsoft and Apple. The ZIP format supports lossless data compression and permits a number of compression algorithms. Although there are several file archivers using ZIP technology, they generally use the ZIP file extension, and archives created through ZIP are often represented by an icon that features a zipper.
File archivers and compression utilities are the focus of topics in this category.
Recommended Resources
Created for the Microsoft Windows platform, a port of the command-line version is available for Linux-type systems. Available as free and open-source software, it is license mostly under the GNU Lesser General Public License, although its source code is under the GNU LGPL with an unRAR restriction which prohibits reverse-engineering the RAR compression algorithm. The features of the 7z format are listed, and the LZMA software development kit (SDK) is highlighted.
https://www.7-zip.org/
Ark is a file archiver and compression utility developed by KDE, It is included in the KDE Applications software bundle, and available as free and open-source (GNU General Public License) software. Within Ark, archives can be created, viewed, extracted, and modified, supporting such formats as TAR, GZIP, BZIP2, ZIP, RAR, and LHA, as long as the appropriate command-line programs are installed. Development notes, documentation, and contacts are included.
https://utils.kde.org/projects/ark/
Created and developed by Robert Rezebek, and marketed through MacItBetter, BetterZip is available for the macOS platform only. For non-commercial use, one license may be used on up to five Macs, although each Mac requires its own license for commercial use. A trial version is available. Unlike the archive utility that is installed with macOS, the archiver is able to compress and extract in several archive formats, as well as including the ability to selectively extract files from an archive.
https://macitbetter.com/
Based on 7Zip technology, jZip is a free compression utility intended to be an alternative to WinZip. Featuring a fast compression engine, it is a tool for unzipping Zip archives, creating Zip-compatible files, and other archiving software, such as RAR and ISO. Promising no adware, spyware, pop-ups, or trojans, jZip is free for home and business users. Its features are listed on the site, and a statement of its reliability is given, along with policy information, and a download link.
https://www.jzip.com/
Available for BSD, Linux, and Windows systems under the terms of the GNU Lesser General Public License, PeaZip is a free and open-source file manager and archiver. It supports its native PEA format, with compression, multi-volume split, flexible authenticated encryption, and integrity check schemes, and other mainstream formats, the program may be freely downloaded from the site, along with plugins and themes. Online support is available in a tutorial and other documentation.
https://www.peazip.org/
Known for its introduction of the ZIP file format, PKZIP was created by Phil Katz and developed by PKWARE, Inc. Originally released for MS-DOS and the IBM-PC compatible platform in 1989, new versions have been released over the years for a number of other architectures and operating systems. Still available from PKWARE, the file compression utility can compress files up to 95%, and can handle more than two billion files in a single archive, and compress files over nine exabytes in size.
https://www.pkware.com/pkzip
Developed by ConeXware, PowerArchiver is a proprietary file archiver for Microsoft Windows. Available in several editions, including a downloadable trial version that is functional for forty days, it can create and read ZIP, TAR, and 7Z formats, as well as various disk image formats, and it can read ACE and RAR files, but not create them. Its editions are highlighted, including a list of features and instructions. A skin library and a user support forum are available.
https://www.powerarchiver.com/
The Unarchiver is a proprietary freeware data compression utility that supports more data formats than the native macOS unpacker utility, and can also handle filenames in various character encodings, but it does not compress files. Originally created for Mac, it now supports Linux and Windows, as well. It is available for download from the site or from the Mac App Store. Its features are highlighted on the site, with instructions, and a list of supported archive formats is given.
https://theunarchiver.com/
Developed by RARLAB, WinRAR is a file archiver utility for the Windows platform. Created by Eugene Roshal, the application can create and view archives in RAR or ZIP formats, and unpack several archive file formats. WinRAR also supports the creation of encrypted, multi-part, and self-extracting archives. While WinRAR is a Windows-only program, an Android application called RAR for Android is also available. It may be purchased online, and a trial version is also available.
https://www.win-rar.com/
Originally released on CompuServe in 1991, WinZip was designed to add a graphical user interface to PKZIP and was a freely downloadable software. Today, a trial version may be downloaded for the Windows, Mac, Android, or iOS platforms, but it is available for purchase in three editions: Standard, Pro, and Pro Combo, the latter of which includes WinZip Courier for zipping email attachments. A Command-Line version is available free for users with a valid license.
https://www.winzip.com/
