What is the difference between :before and ::before?

Question

I just saw a CSS code that included ::before tag. I looked at MDN to see what the ::before is but I really didn\'t understand it.

Can some

Answer 1

One is the CSS2 (:before) way and the other is CSS3 (::before). Currently they are interchangeable in browsers that support CSS2 & CSS3.

Here's a good explanation: http://www.impressivewebs.com/before-after-css3/