title: What is com.sun.proxy.$Proxy
body: <p>I have seen that when errors occur deep in different frameworks (e.g frameworks implementing the EJB specification or some JPA providers) the stacktrace contain classes like <code>com.sun.proxy.$Proxy</code>. I know what a Proxy is, but I am looking for a more technical and more java specific answer.</p>
  
  <ol>
  <li>What are they?</li>
  <li>How are they created?</li>
  <li>What is there relationship to the JVM? Are they JVM implementation specific?</li>
  </ol>