When should you branch?

Question

When working with a SCM system, when should you branch?

Answer 1

There are various purposes for branching:

1. Feature/bug branches. Dynamic and active branches that get moved back into the trunk when the feature/bugfix is complete.
2. Static branches (tags in Subversion, though in essence just a 'normal branch'). They provide a static snapshot of say, a release. Even though they could be worked on, they remain untouched.