CSS - Line height property, how it works (simple)

Question

So in this simple example I have as final result:

This is a very simple question but I sim

Answer 1

Essentially the line-height helps to set the "leading" and "half-leading". The 100px accounts for the total height of the element and the text is being "vertically aligned" within that area. Half is going above and half below.

This explains better than I. http://www.w3.org/TR/CSS2/visudet.html#line-height