By Eric Sink There are several reasons why we may need to merge two modified versions of a file: When using "edit-merge-commit" (sometimes called "optimistic locking"), it is possible for two developers to edit the same file at the same time. Even if we use "checkout-edit-checkin", we may allow multiple checkouts, resulting once again in the possibility of two developers editing the same file. When merging between branches, we may have a situation where the file has been modified in both branches. In other words, this mess only happens when people are working in parallel. If we serialize the efforts of our team by never branching and never allowing two people to work on a module at the same time, we can avoid ever facing the need to merge two versions of a file.