There are (unfortunately) a lot of git repositories with multiple long-lived branches, often to track what's released in different environments. Unfortunate because it leads to a _ton_ of merge conflicts and uncertainty about what code is live in what env.
One of the most popular of these flows was popularized under the brand "Gitflow". Atlassian has a detailed, and critical, writeup of that here: https://www.atlassian.com/git/tutorials/comparing-workflows/...