title: When to use nil, blank, empty?
body: <p>Is there any guidelines on how to differentiate between <code>.nil?</code>, <code>.blank?</code> and <code>.empty?</code>?</p>
  
  <p>I'm generally always confused as to when to use them in my application as they all seem to mean the same thing but have different meanings.</p>
  
  <p>Does anyone have any cheat sheet on the gory details?</p>