HEAD in Git and It’s importance
Git is a version control system that is widely used for software development and other version control tasks. It is a distributed version control system with an emphasis on speed, data integrity, and support for distributed, non-linear workflows. Git was initially designed and developed in 2005 by Linux Kernel developers (including Linus Torvalds) for Linux kernel development.
HEAD in Git is a reference to the last commit in the currently checked-out branch. There is a small exception to this, which is the detached HEAD. A detached HEAD is the situation you encounter whenever you check out a commit (or tag) instead of a branch.
It’s also possible to have a “detached HEAD” when you check out something besides a (local) branch, like a remote branch, a specific commit, or a tag. The most common place to see this is during an interactive rebase, when you choose to edit a commit. In detached HEAD state, your HEAD is a direct reference to a commit — the contents of .git/HEAD will be a SHA1 hash.
Generally speaking, HEAD is just a convenient name to mean “what you have checked out” and you don’t really have to worry much about it. Just be aware of what you have checked out, and remember that you probably don’t want to commit if you’re not on a branch (detached HEAD state) unless you know what you’re doing (e.g. are in an interactive rebase).