[ajit22]

Usually attributes are assigned just one class, but this doesn't mean that that's all you're allowed. In reality, you can assign as many classes as you like! For example:

<p class="text side">...</p>

Using these two classes together (separated by a space, not with a comma) means that the paragraph calls up the rules assigned to both text and side. If any rules overlap between the two classes then the class which is below the other in the CSS document will take precedence.

[Yeroon]

If any rules overlap between the two classes then the class which is below the other in the CSS document will take precedence

Isn't this different for IE and FF? I will look into that. Thought that IE looks at the first one.

[job0107]

if .text says border:1px solid #000; and .side says border:2px solid #000;

Then you have this element:
<p class="text side">...</p>

Then the element will end up with a 2px border, regardless which browser you view it in.

[Yeroon]

Tried it and guess you are right. IE6, IE7 and FF all show the same. I can't test on FF 2 anymore though. Somehow I thought I remembered there was a difference, but guess not.