css layout property clear and clearfix

Question

I have read clear is css layout property

But what about clearfix its css property or what else.

It may be use for float layout.

But I want explanation on css clearfix Is this property of css or this is user define class or what

I know the way i am asking question is confusing

But I want to know is clearfix iscss class or user defined

Thanks

Answer 1

After searching net I found this article

http://thinkvitamin.com/design/everything-you-know-about-clearfix-is-wrong/