title: Understanding scenes in Unity3d
body: <p>I have some confusion with scenes in Unity3d and I was not able to find any resources about them.</p>
  
  <ol>
  <li>When should scenes be used? For example in a platformer would every level have to be a different scene? Would the main menu be a scene?</li>
  <li>Can one overlay scenes? </li>
  <li>How do assets work between scenes? Are they attached to each individual scene and have to be reloaded every time. Can one specify when an asset is no longer needed?</li>
  <li>How does one send data between scenes/interface between scenes?
  I understand that this is a broad topic, but I didn't want to spam with multiple questions.</li>
  </ol>