docs/data/reusables/rest-reference/git/refs.md

References

A Git reference (git ref) is just a file that contains a Git commit SHA-1 hash. When referring to a Git commit, you can use the Git reference, which is an easy-to-remember name, rather than the hash. The Git reference can be rewritten to point to a new commit. A branch is just a Git reference that stores the new Git commit hash. These endpoints allow you to read and write references to your Git database on {% data variables.product.product_name %}.