Git is a free, open source distributed version control system (DVCS) designed to handle everything from small to very large projects with speed and efficiency.
In addition to working as a DVCS, Git also acts as a local repository, a place where the complete history of your work is stored. When you use Git, your file history is stored in a .git subdirectory of your working copy, so you can work with your full revision history without requiring connection to a central server.
This article will serve as an introduction to what a Git Repository is all about.
Git is a distributed version control system. It originated from Linux kernel development, and is used by many popular open source projects, such as the Android or the Eclipse development teams, as well as many commercial organizations. The core of Git was originally written in the programming language C, but Git has also been re-implemented in other languages, such as Java, Ruby, and Python, although the main development continues in C.
There are two main approaches to a Git project:
After cloning or creating a repository, the user will have a complete copy of the repository. He can then perform version control operations against this local repository. If he so chooses, he can configure the repository as a bare or a non-bare variant.
Bare repositories are only used on servers to share changes coming from different developers, and contain no local changes. Non-bare repositories let you make changes via the modification of your working copy files. This also allows you to create new versions in the repository.
If you want to delete a Git repository, you can simply delete the folder which contains the repository.
Git also allows the user to synchronize the local repository with other remote repositories. Users with sufficient authorization can push changes from their local repository to remote repositories. They can also fetch or pull changes from other repositories and bring these changes to their local Git repository.
Git supports branching, which means that you can work on different versions of your collection of files. A branch separates these different versions, and allows the user to switch between these versions to work on them. Branches in Git are local to the repository, although it is possible to push branches to a central Git repository if you wish to share them with other users.
A branch created in a local repository, which was cloned from another repository, does not need to have a counterpart in the remote repository. Local branches can be compared with other local branches, and with remote tracking branches. A remote tracking branch proxies the state of a branch in another remote repository. Git supports the changes from different branches, and they can be combined through a system which also allows developers to automate such a process.
Choosing a repository for your software project is not unlike choosing where to host a website. The option you choose will depend on your circumstances, particularly the functionality you require, the amount of effort required to manage the project, the popularity of the service amongst the community you work in, and the size and diversity of contributors to your project.
Compared to other version control systems such as Subversion (SVN), an individual Git repository tends to be used for only one project, or perhaps even only one component of a larger project. This compares with SVN, where an organization may choose to have one repository that contains many independent projects. This separation is usually done to reduce network bandwidth, since cloning a Git repository involves copying the complete history of the project.
Many developers now prefer to use a distributed version control system such as Git over a more centralized system. The speed and convenience of always having a full repository history available locally can provide a significant productivity boost, while the improved branching merging options allow for many different development workflow scenarios that were difficult or not possible before.
These additional features and flexibility do come at a cost however, with the Git commands being considerably more complex to learn and master than other version control systems. However, once developers make the investment to learn Git they will begin to reap the benefits of this new approach to version control.