title: How to set up a typical users HABTM roles relationship
body: <p>I'm quite new to this and I'm using cancan + devise for my user auth. However I'm not really sure what it means to set up a typical users HABTM roles relationship nor do I really understand what a HABTM relationship is.</p>
  
  <p>Can anyone explain it really well or point me to a good tutorial or example?</p>