When does whitespace matter in HTML?

Question

example 1

onetwo


    one
    <         


        
      

Answer 1

HTML collapses serial whitespaces to a single whitespace, but doesn't eliminate it. A newline is a whitespace, therefore a space.

It's not just leading/trailing - serial whitespace within an element is rendered as single whitespace as well. These will render identically:

   a   b   
 a b 
a b