Git ( ) is a distributed version control software system that is capable of managing versions of source code or data. It is often used to control source code by programmers who are developing software collaboratively. It was originally created by Linus Torvalds for version control in the development of the Linux kernel.
Design goals of Git include speed, data integrity, and support for distributed, non-linear workflows—thousands of parallel branches running on different computers.
As with most other distributed version control systems, and unlike most client–server systems, Git maintains a local copy of the entire repository, also known as the "repo", with history and version-tracking abilities, independent of network access or a central server. A repository is stored on each computer in a standard directory with additional, hidden files to provide version control capabilities. Git provides features to synchronize changes between repositories that share history; for asynchronous collaboration, this extends to repositories on remote machines. Although all repositories (with the same history) are peers, developers often use a central server to host a repository to hold an integrated copy.
Today, Git is the version control system most commonly used by software developers. It is the most popular distributed version control system, with nearly 95% of developers reporting it as their primary version control system as of 2022. It is the most widely used source-code management tool among professional developers. Several different software forges offer Git repository services, including GitHub, SourceForge, Bitbucket and GitLab.
Torvalds started developing Git in April 2005 after the free license for BitKeeper, the proprietary source-control management (SCM) system used for Linux kernel development since 2002, was revoked for Linux. The copyright holder of BitKeeper, Larry McVoy, claimed that Andrew Tridgell had created SourcePuller by reverse engineering the BitKeeper protocols. The same incident also spurred the creation of Mercurial, another version-control system.
Torvalds wanted a distributed system that he could use like BitKeeper, but none of the available free systems met his needs. He cited an example of a source-control management system needing 30 seconds to apply a patch and update all associated metadata, and noted that this would not scale to the needs of Linux kernel development, where synchronizing with fellow maintainers could require 250 such actions at once. For his design criterion, he specified that patching should take no more than three seconds, and added three more goals:
Take the Concurrent Versions System (CVS) as an example of what not to do; if in doubt, make the exact opposite decision.
Support a distributed, BitKeeper-like workflow.
Include very strong safeguards against corruption, either accidental or malicious.
These criteria eliminated every version-control system in use at the time, so immediately after the 2.6.12-rc2 Linux kernel development release, Torvalds set out to write his own.
The development of Git began on 3 April 2005. Torvalds announced the project on 6 April and became self-hosting the next day. The first merge of multiple branches took place on 18 April. Torvalds achieved his performance goals; on 29 April, the nascent Git was benchmarked recording patches to the Linux kernel tree at a rate of 6.7 patches per second. On 16 June, Git managed the kernel 2.6.12 release.
Torvalds turned over maintenance on 26 July 2005 to Junio Hamano, a major contributor to the project. Hamano was responsible for the 1.0 release on 21 December 2005.
Torvalds quipped about the name git (which is British English slang for an unpleasant or silly person): "I'm an egotistical bastard, and I name all my projects after myself. First 'Linux', now 'git'." The man page describes Git as "the stupid content tracker".
The read-me file of the source code elaborates further:
"git" can mean anything, depending on your mood.
Random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
Stupid. Contemptible and despicable. Simple. Take your pick from the dictionary of slang.
"Global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.