title: what is Dependency Injection?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/130794/what-is-dependency-injection">What is dependency injection?</a>  </p>
  </blockquote>
  
  
  
  <p>Im learning asp.net mvc 3. One of the new features being Dependency Injection. Can someone tell me what it is? why is it useful? and when to use it? Thanks</p>