title: When to use git subtree?
body: <p>What problem does <code>git subtree</code> solve?
  When and why should I use that feature?</p>
  
  <p>I've read that it is <a href="https://makingsoftware.wordpress.com/2013/02/16/using-git-subtrees-for-repository-separation/">used for repository separation</a>. But why would I not just create two independent repositories instead of sticking two unrelated ones into one?</p>
  
  <p>This GitHub tutorial explains <a href="https://help.github.com/articles/about-git-subtree-merges/">how to perform Git subtree merges</a>.</p>
  
  <p>I kind of know <em>how</em> to use it, but not <em>when</em> (use cases) and <em>why</em>, and how it relates to <a href="https://git-scm.com/book/en/v2/Git-Tools-Submodules"><code>git submodule</code></a>. I'd use submodules when I have a dependency on another project or library.</p>