There has been an unmistakable trend in the development and use of revision control tools over the past four decades, as people have become familiar with the capabilities of their tools and constrained by their limitations.
The first generation began by managing single files on individual computers. Although these tools represented a huge advance over ad-hoc manual revision control, their locking model and reliance on a single computer limited them to small, tightly knit teams.
The second generation loosened these constraints by moving to network-centered architectures and managing entire projects at a time. As projects grew larger, they ran into new problems. With clients needing to talk to servers very frequently, server scaling became an issue for large projects. An unreliable network connection could prevent remote users from being able to talk to the server at all. As open source projects started making read-only access available anonymously to anyone, people without commit privileges found that they could not use the tools to interact with a project in a natural way, as they could not record their changes.
The current generation of revision control tools is peer-to-peer in nature. All of these systems have dropped the dependency on a single central server, and allow people to distribute their revision control data to where it’s actually needed. Collaboration over the Internet has moved from being constrained by technology to a matter of choice and consensus. Modern tools can operate offline indefinitely and autonomously, with a network connection only needed when syncing changes with another repository.
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