title: What is the difference between README and README.md in GitHub projects?
body: <p>I've noticed some GitHub projects have not only a <code>README</code> file, but also a <code>README.md</code> file.</p>
  
  <p>What is the difference between these files? I know <code>README</code> serves also as introductory text in the project repository page but I have no idea what <code>README.md</code> does.</p>