Source control, also known as version control, is a system that helps manage changes to files, particularly in software development. It allows multiple people to work on the same project simultaneously without overwriting each other's work. By keeping a history of changes, source control makes it easy to track modifications, revert to previous versions, and collaborate effectively. Popular source control systems include Git, Subversion, and Mercurial. These tools enable developers to create branches for new features, merge changes, and resolve conflicts. Source control is essential for maintaining code quality and ensuring that projects remain organized and manageable over time.