computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and softw ...

, an archive file stores the content of one or more files, possibly compressed, with associated metadata such as file name, directory structure, error detection and correction information, commentary, compressed data archives, storage, and sometimes encryption. An archive file is often used to facilitate portability, distribution and backup, and to reduce storage use.

Applications

Portability

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. Also, transfer of a single archive file may be faster than processing multiple files due to per-file overhead, and even faster if compressed.

Software distribution

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. Examples include deb for

Debian Debian () is a free and open-source software, free and open source Linux distribution, developed by the Debian Project, which was established by Ian Murdock in August 1993. Debian is one of the oldest operating systems based on the Linux kerne ...

, JAR for

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

, APK for Android, and self-extracting Windows Installer executables.

Features

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

Error detection and recovery

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). 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.

Format

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. As is common for all files, the format of an archive is generally indicated by file name extension and/or file header. Commonly used formats include zip, rar, 7z, and tar.

introduced archive formats including jar (''j'' for Java) and war (''w'' for web) that store an entire runnable deployment; usually compressed.

References

"Application Note on the .ZIP file format"
official white paper published by PKWARE, Inc.
Tape Archive (.TAR) file format specification
excerpt from File Format List 2.0 by Max Maischein

from IBM Archives

from IBM Archives

External links

{{Archive formats Computer files Computer archives Computer file systems Disk images Records management