The purpose of a version control system (VCS) in collaborative coding is to manage changes to source code over time. It allows multiple developers to work simultaneously without conflicts, tracking every modification to the codebase. A VCS provides features like branching, which enables parallel development of features, and merging, which integrates changes from different contributors. Additionally, it maintains a history of changes, aiding in troubleshooting and reverting to previous states if necessary. This makes collaborative coding more efficient and organized.