Darcs is a free, open source revision control system. It is: Distributed: Darcs was one of the first revision control systems in which every user has access to the full command set, removing boundaries between server and client or committer and non-committers. Interactive: Darcs is easy to learn and efficient to use because it asks you questions in response to simple commands, giving you choices in your work flow. You can choose to record one change in a file, while ignoring another. As you update from upstream, you can review each patch, picking and choosing which patches are appropriate. Smart: Darcs is different from most revision control systems in that it is based on the notion of change (or patch), rather than version. An underlying algebra of patches determines whether changes can be re-ordered. The laws of this algebra guarantee that the result of merging depends only on the final set of patches applied in a repository and not on their order. Simple: As a consequence, Darcs offers a conceptually simpler view of the state of a repository: it is given by the set of patches it contains. Pulling and pushing patches merely transfers them from one set to another. So called "cherry-picking" is the default mode of operation, and it fully preserves the identity of patches.