Submodules are great for projects where your code depends on upstream Git repos that you don't control and don't want to vendor yourself. I recently did an emb

Submodules are great for projects where your code depends on upstream Git repos that you don't control and don't want to vendor yourself. I recently did an embedded Linux design that depended on 5 external repositories: one from Yocto, three from OpenEmbedded, and one from a CPU vendor. My own code just sat on the top of this set of repos. Submodules made that design very simple. One repo with all of my code in it, and submodules for all external repos. All dependent repos were pinned before of how submodules work. Pins were easy to update when desired, and never move on their own.