What is HEAD in Git?

Question

You see the Git documentation saying things like

The branch must be fully merged in HEAD.

But what is Git HEAD exac

Answer 1

As a concept, the head is the latest revision in a branch. If you have more than one head per named branch you probably created it when doing local commits without merging, effectively creating an unnamed branch.

To have a "clean" repository, you should have one head per named branch and always merge to a named branch after you worked locally.

This is also true for Mercurial.