Centralized version control systems were created to make it possible for multiple collaborators to work on projects together. In these systems, the history of revisions is stored on a central server, and all the version control operations by all collaborators must go through this server. If a collaborator records a new revision, then all other collaborators can download and apply the revision in their own environments to update their project to the same state as the central server:

To avoid conflicting changes on the same file by multiple collaborators, such as concurrent modifications to the same lines, collaborators have to work in lockstep—after collaborator A has made some changes, collaborator B must first download those changes before he can add any new changes of his own.

Thanks to its simplicity, this is still a very popular workflow today, used by many large and famous projects and organizations. However, despite their popularity, centralized systems have serious drawbacks: