Archive file#Archive formats

As an archive file stores file system information, including file content and metadata, it can be leveraged for file system content portability across heterogeneous systems. For example, a directory tree can be sent via email, files with unsupported names on the target system can be renamed during extraction, timestamps can be retained rather than lost during data transmission.{{Cite web |title=Data Portability and Platform Competition {{!}} Is User Data Exported From Facebook Actually Useful to Competitors? |url=https://archive.org/details/data_portability_and_platform_competition_-_is_user_data_exported_from_facebook_ |access-date=June 17, 2022 |website=Archive.org |pages=22}} Also, transfer of a single archive file may be faster than processing multiple files due to per-file overhead,{{Cite web |date=2020-06-17 |title=Why file transfer speeds of small vs large files could be different |url=https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/Why_file_transfer_speeds_of_small_vs_large_files_could_be_different |access-date=2022-06-17 |website=NetApp Knowledge Base |language=en |archive-date=2022-01-01 |archive-url=https://web.archive.org/web/20220101141232/https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/Why_file_transfer_speeds_of_small_vs_large_files_could_be_different |url-status=live }}{{Cite web |date=2018-10-10 |title=Why Small Files Take Longer to Copy Than Large Files |url=https://www.dq-int.co.uk/blog/why-small-files-take-longer-to-copy-than-large-files/ |access-date=2022-06-17 |website=Dataquest |language=en-GB |archive-date=2022-07-02 |archive-url=https://web.archive.org/web/20220702161208/https://www.dq-int.co.uk/blog/why-small-files-take-longer-to-copy-than-large-files/ |url-status=live }} and even faster if compressed.

Beyond archiving, archive files are often used for software distribution. When used in connection with a package manager, an archive must conform to a package format and is called a package. In particular, the format usually requires a manifest file.{{Cite web |first=Amit |last=Ashbel |title=Data Archiving: The Basics and 5 Best Practices |url=https://cloud.netapp.com/blog/clc-blg-data-archiving-the-basics-and-5-best-practices |access-date=2022-06-17 |website=cloud.netapp.com |language=en-us |archive-date=2022-01-19 |archive-url=https://web.archive.org/web/20220119105316/https://cloud.netapp.com/blog/clc-blg-data-archiving-the-basics-and-5-best-practices |url-status=live }} Examples include deb for Debian, JAR for Java, APK for Android, and self-extracting Windows Installer executables.

Notable features supported for various archives include:

• Concatenate multiple files in a single file
• Store file metadata as data, including file name, timestamps, permissions, source storage, notes and description
• Compression
• Encryption
• Error detection via checksums
• Error correction code to fix errors
• Splitting a large file into multiple, smaller files
• File patches/updates (when recording changes since a previous archive)
• Self-extraction
• Self-installation

Archive files often include parity checks and other checksums for error detection, for instance zip files use a cyclic redundancy check (CRC). RAR archives may include additional error correction data (called recovery records).{{Cite book |last=Drummond |first=James R. |url=https://faraday.physics.utoronto.ca/PVB/Drummond/Micro/ln_comm1.pdf |title=Parity, Checksums and CRC Checks |year=1997 |edition=1st |location=Toronto |pages=13 |language=En |access-date=2022-06-17 |archive-date=2020-10-31 |archive-url=https://web.archive.org/web/20201031235541/https://faraday.physics.utoronto.ca/PVB/Drummond/Micro/ln_comm1.pdf |url-status=live }}

Archive files that do not natively support recovery records can use separate parchive (PAR) files that allows for additional error correction and recovery of missing files in a multi-file archive.{{Cite web |last=text |title=What are PAR and PAR2 Files? |url=https://help.easynews.com/kb/article/72-what-are-par-and-par2-files/ |access-date=2022-06-17 |website=Easynews |language=en |archive-date=2024-07-11 |archive-url=https://web.archive.org/web/20240711021759/https://help.easynews.com/kb/article/72-what-are-par-and-par2-files/ |url-status=live }}

{{anchor|archive formats}}

The format of an archive file is its archive format. Some formats are well-defined and some have become conventions supported by multiple vendors and communities.{{Cite web |title=What are Archive Files? |url=https://www.exefiles.com/en/extensions/file-types/archive/ |access-date=2022-06-17 |website=www.exefiles.com |archive-date=2022-05-28 |archive-url=https://web.archive.org/web/20220528110322/https://www.exefiles.com/en/extensions/file-types/archive/ |url-status=live }} As is common for all files, the format of an archive is generally indicated by file name extension and/or file header.{{Cite web |title=What Is a File Extension & Why Are They Important? |url=https://www.lifewire.com/what-is-a-file-extension-2625879 |access-date=2022-06-17 |website=Lifewire |language=en |archive-date=2022-06-03 |archive-url=https://web.archive.org/web/20220603202723/https://www.lifewire.com/what-is-a-file-extension-2625879 |url-status=live }}

Commonly used formats include zip, rar, 7z, and tar.{{Cite web |title=Common file name extensions in Windows |url=https://support.microsoft.com/en-us/windows/common-file-name-extensions-in-windows-da4a4430-8e76-89c5-59f7-1cdbbc75cb01 |access-date=2022-06-17 |website=support.microsoft.com |archive-date=2022-05-27 |archive-url=https://web.archive.org/web/20220527200605/https://support.microsoft.com/en-us/windows/common-file-name-extensions-in-windows-da4a4430-8e76-89c5-59f7-1cdbbc75cb01 |url-status=live }} Java introduced archive formats including jar (j for Java) and war (w for web) that store an entire runnable deployment; usually compressed.{{Cite web |last=Malefanem |first=Moses |title=Learning Java Network Programming |url=https://www.academia.edu/21445522 |access-date=2022-06-17 |archive-date=2023-09-07 |archive-url=https://web.archive.org/web/20230907003607/https://www.academia.edu/21445522 |url-status=live }}

• {{Annotated link|Comparison of archive formats}}
• {{Annotated link|Digital container format}}
• {{Annotated link|Disk image}}
• {{Annotated link|File archiver}}
• {{Annotated link|List of archive formats}}

{{Reflist}}

• [http://www.pkware.com/documents/casestudies/APPNOTE.TXT "Application Note on the .ZIP file format"]- official white paper published by PKWARE, Inc.
• [https://web.archive.org/web/20090611043446/http://datacompression.info/ArchiveFormats/tar.txt Tape Archive (.TAR) file format specification]- excerpt from File Format List 2.0 by Max Maischein
• [https://web.archive.org/web/20050122223045/http://www-03.ibm.com/ibm/history/exhibits/701/701_1415bx26.html "IBM 726 Magnetic tape reader/recorder] from IBM Archives
• [https://web.archive.org/web/20120702230325/http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP1401.html "1401 Data Processing System"] from IBM Archives

{{Archive formats}}

Category:Computer files

Category:Computer archives

Category:Computer file systems

Category:Disk images

Category:Records management