# Version Control Systems

Version control/source control systems allow developers to track and control changes to code over time. These services often include the ability to make atomic revisions to code, branch/fork off of specific points, and to compare versions of code. They are useful in determining the who, what, when, and why code changes were made.


<ResourceGroupTitle>Free Content</ResourceGroupTitle>
<BadgeLink colorScheme='blue' badgeText='Official Website' href='https://git-scm.com/'>Git</BadgeLink>
<BadgeLink colorScheme='blue' badgeText='Official Website' href='https://www.mercurial-scm.org/'>Mercurial</BadgeLink>
<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.atlassian.com/git/tutorials/what-is-version-control'>What is Version Control?</BadgeLink>