title: what does git merge origin/master do?
body: <p>After fetching from remote using <code>git fetch</code>, we need to use something like</p>
  
  <pre><code>git merge origin/master
  </code></pre>
  
  <p>I would like to know if this command also does <code>git commit</code> at the same time? Is the order <code>origin/master</code> important? Can I write <code>master/original</code>?</p>