How are the terms “HEAD”, “head”, and “tip” different?

Question

Initial Understanding

HEAD

• \"indicates the head of the current branch.\"
• so, there is only one HEAD.

head

Answer 1

Branches (a.k.a. branch heads) mark points of interests in your repo. The metaphor isn't perfect, but you can think of branches as some sort of "bookmarks". Each branch points to a commit; that commit is called the tip of the branch.

HEAD (note the uppercase) is different. It usually points to a branch, indicating which point of interest in your repo you're currently at. However, in some cases, HEAD may also point directly to a commit (in which case your repo is said to have a "detached HEAD").

You can think of HEAD as

1. a "you-are-here" marker on the metro map that is your commit graph; or
2. an indicator of which branch (if any) is currently checked out.

For instance, in the following repository, the tip of the master branch is the commit of abbreviated ID f42c5; the tip of the develop branch is the commit of abbreviated ID 190a3; HEAD points to master, indicating that master is currently checked out.