title: CSS3 visual formatting model
body: <p>I'm confused by what is written in the specification on the box model in that 
  <strong>it generates for each element 0 or more boxes</strong> but I do not understand when an element may generate 0 box.
  In fact in the specification is also said that <strong>each element generates a box</strong>.</p>
  
  <p>Thanks.</p>