The main purpose of version control systems (VCS) is to manage changes to source code over time. They allow multiple developers to collaborate on projects without overwriting each other's work. VCS tracks revisions, enabling teams to revert to previous states of the codebase, compare changes, and maintain a history of modifications. Popular systems, such as Git and Subversion, facilitate efficient collaboration and help prevent conflicts during the development process. Overall, VCS enhances code quality and supports software maintenance.