<div id="wrapper">

Hey there Rosemary,

The web browsers keep track of which div you will be closing when you close a div with the </div> closing tag.

Because of the way html elements have to be 'nested' there is no ambiguity about which element you are closing, ie if you have to close all elements inside an element before closing the element.

Sometimes when I found it difficult to keep track of which element was inside of which I would comment the closing tags to help me keep track.

<div id="mainDiv">
  <div id="innerDiv">
  </div>  <!-- closing innerDiv -->
</div> <!-- closing mainDiv -->

but the browser doesn't need this to keep track.

What can those browsers not do! Thanks so much for your answer and for your solution for keeping track. Appreciate it, so fast too!

Very good! : )