A software repository is a storage location from which software packages may be retrieved and installed on a computer.
Overview
Many software publishers and other organizations maintain servers on the Internet for this purpose, either free of charge or for a subscription fee. Repositories may be solely for particular programs, such as CPAN for the Perl programming language, or for an entire operating system. Operators of such repositories typically provide a package management system, tools intended to search for, install and otherwise manipulate software packages from the repositories. For example, many Linux distributions use Advanced Packaging Tool (APT), commonly found in Debian based distributions, or yum found in Red Hat based distributions. There are also multiple independent package management systems, such as pacman, used in Arch Linux and equo, found in Sabayon Linux.
As software repositories are designed to include useful packages, major repositories are designed to be malware free. If a computer is configured to use a digitally signed repository from a reputable vendor, and is coupled with an appropriate permissions system, this significantly reduces the threat of malware to these systems. As a side effect, many systems that have these capabilities do not require anti-malware software such as anti-virus software.
Most major Linux distributions have many repositories around the world that mirror the main repository.
Package management system vs. package development process
A package management system is different from a package development process.
A typical use of a package management system is to facilitate the integration of code from possibly different sources into a coherent stand-alone operating unit. Thus, a package management system might be used to produce a distribution of Linux, possibly a distribution tailored to a specific restricted application.
A package development process, by contrast, is used to manage the co-development of code and documentation of a collection of functions or routines with a common theme, producing thereby a package of software functions that typically will not be complete and usable by themselves. A good package development process will help users conform to good documentation and coding practices, integrating some level of unit testing.
