About

A ref (or reference) is a human-readable name given to a commit SHA-1 hash.

When referring to a Git commit, you can refer it by name with a reference

A Git reference can be rewritten to point to a new commit.

Refs are:

• branches (A ref that stores the new Git commit hash.)
• and/or tags

There is also symbolic refs (alias ref) point to a ref instead of directly pointing to a commit, the most common being HEAD

Ref to a SHA commit

All SHA commit are in file located under the directory git dir/refs

Example for a head

cat .git/refs/heads/main

db393705d7bb3b8a1c155976082c6ee5691e678e

Remote Heads Refs

remote head refs

git ls-remote --heads remote

# default
git ls-remote --heads origin

dd39a644a4a7ec3e65135baaf48acd5f7f628510        refs/heads/master
6ead0945771dfd789aa97442ff10872f9665598d        refs/heads/stable
e245797039fa7b86c3a3fb32b45cfb998d8c76cd        refs/heads/v1.13

Git Repo

Physically, it's is a file under the refs directory in the repository directory that contains the commit hash.

Pull request

For Pull request such as Github Pull request, the ref value would be refs/pull/421/merge.