space in html

    <!-- 1 space -->
 	<!-- tab; 2 space -->
 	<!-- tab; 4 space -->	non-breaking space	=  
<	less than =	<
>	greater than =	>
&	ampersand =	&<br/>Html whitespace# in CSS means your looking at an ID so 
<div class="ExampleClass" id="ExampleID"></div>

#ExampleID would reference the ID
.ExampleClass would reference the class