title: Linq-to-Entities Join vs GroupJoin
body: <p>Can someone please explain what a <code>GroupJoin()</code> is?</p>
  <p>How is it different from a regular <code>Join()</code>?</p>
  <p>Is it commonly used?</p>
  <p>Is it only for method syntax? What about query syntax? (A c# code example would be nice)</p>