what is head in git?

From this StackOverflow answer:

I always thought HEAD~5 means GO to 5 commits before. But it doesn’t carry the GO part of the command. It only carries the reference/‘where to’ part of the command.

In layman terms it’s used to answer the question of: WHERE should I go? To which commit?

• HEAD means (the reference to the) current commit
• HEAD~1 means (the reference to) 1 commit before
• HEAD~ ALSO means (the reference to) 1 commit before
• HEAD~87 means (the reference to) 87 commits before

Usage:

git checkout HEAD~1 will actually GO/checkout to that reference/commit

git reset HEAD~3 will uncommit your last 3 commits — without removing the changes, ie you can see all the changes made in the last 3 commits together, remove anything you don’t like or add onto it and then commit them all again.

git diff HEAD~3 for checking changes in the last 3 commits

HEAD, then, is a pointer to the tip of the commit history. It can be used to generate a new reference to navigate the history.