Might be slightly off topic, just still relevant to the question
https://git-scm.com/book/en/v2/Git-Tools-Submodules
Git Submodules are git repos that you can use in other repos (henceforth, referred to as Supermodules). With each submodule having the usual assortment of branches features and tags, the benefit comes from each supermodule being a version controlled, pluggable components, that can be worked on separately or developed alongside the supermodule.
A Few Useful Commands
To add a submodule, you run the following inside your supermodule:
git submodule add <url-to-submodule-repo>
The submodule(s) still have to be initialized and fetched from the repo:
git submodule init
git submodule update
A supermodule with submodules can be cloned and all submodules fetched by running:
git clone --recursive <url-to-supermodule>
You can pull upstream changes to a submodule's branch by running the following inside the submodule directory:
git fetch
Then run the following to update local code:
git merge
The following will fetch and merge for all submodules in your supermodule:
git submodule update --remote
If you want to track a specific branch of a submodule you can use the following:
git config -f .gitmodules submodule.<my-submodule>.branch fantastic_new_implementation
If you have worked on your supermodules and submodules and you push your supermodule, changes made to submodules will only exist locally and those you are collaborating with will not know of these changes.
The following command will check if your submodules have been pushed BEFORE attempting to push your supermodule
git push --recurse-submodules=check
Finally, here is a useful ForEach command, that allows us to run a command for each submodule
git submodule foreach 'git checkout -b featureA