In order to remember what a branch was for, you should give it a good name! I usually use git flow, so I have branches, like
master
develop
feature/skydome
feature/quest-system
feature/magic-system
hotfix/issue-123
hotfix/double-jump
As you can see, you can even use your issue tracker to maintain a detailed description and just name the branch in a way that makes it obvious where to look.