What is HEAD

HEAD is Git's pointer to your current position in the repository. Understanding HEAD helps you navigate history, create branches at the right point, and understand what commands like git reset and git diff HEAD are actually doing.

What is HEAD?

HEAD is a reference that points to the commit you currently have checked out. Most of the time, HEAD points to a branch name (like main), which in turn points to the latest commit on that branch.

View what HEAD points to:

cat .git/HEAD

Output when on a branch:

ref: refs/heads/main

HEAD and Branches

When you make a new commit, two things happen:

1. A new commit object is created.
2. The current branch pointer (e.g., main) moves forward to that commit.
3. HEAD stays pointing to the branch, so it implicitly moves too.

Detached HEAD State

If you check out a specific commit hash, tag, or remote branch without creating a local branch, HEAD points directly to a commit rather than a branch. This is called "detached HEAD" state.

git checkout a3f6f1c

Git warns you:

HEAD is now at a3f6f1c Add navigation bar
You are in 'detached HEAD' state.

In detached HEAD state, you can look around and run tests. But if you make commits, they won't belong to any branch and will be lost when you switch away unless you create a branch first.

Create a Branch from Detached HEAD

If you've made commits in detached HEAD state and want to keep them:

git checkout -b my-experiment

Referencing Commits Relative to HEAD

HEAD~1 means one commit before HEAD. HEAD~2 means two commits before, and so on.

Show the commit before the current one:

git show HEAD~1

Diff the last two commits:

git diff HEAD~1 HEAD

Return to a Branch from Detached HEAD

git checkout main

tip

Think of HEAD as a bookmark. On a branch, it moves forward automatically as you commit. In detached state, it points to a fixed commit until you move it yourself.

Common Mistakes

Making commits in detached HEAD state without creating a branch — those commits become "dangling" and are cleaned up by Git's garbage collector eventually. Create a branch (git checkout -b <name>) as soon as you realise you want to keep the work.

Confusing HEAD with origin/HEAD — origin/HEAD is the default branch on the remote, not your local position. HEAD is always your local current position.

Using HEAD~ syntax incorrectly in merge commits — merge commits have two parents. HEAD~1 follows the first parent. Use HEAD^2 to follow the second parent (the merged branch).

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Next Steps: Navigating with git checkout