title: delegateEvents in backbone.js
body: <p>Can anyone please explain me what delegateEvents in backbone.js does? <a href="http://backbonejs.org/#View-delegateEvents">The documentation</a> did not help me to understand.</p>
  
  <p>My exact use case is:</p>
  
  <p>I have a main view X with an inner view Y. They work great, but if I go to main view Z and then go back to X (reusing, not recreating) then events attached to Y child elements get lost. delegateEvents solves this but 
  I want to understand why.</p>