That’s not quite right is it? HEAD is simply a pointer to whatever commit is currently on disk.
HEAD can point to a commit that is the end of a branch (typical state, HEAD is “attached”), but it can also point to one that isn’t (HEAD is “detached”).
HEAD can point to a commit that is the end of a branch (typical state, HEAD is “attached”), but it can also point to one that isn’t (HEAD is “detached”).