There’s plenty of controversy between developers about whether or not we should continue to support IE6, especially with the addition of CSS3 and HTML5. No matter what side of the IE6 fence you’re on, you should understand that a website cannot, and should not, look exactly the same in every browser.

Progressive Enhancement
Image credit: bioxid

This is the case because not every browser can support all the different tech nology that exists today. As such, developers must decide between two choices:

To show main source of content:
http://www.onextrapixel.com/2010/03/26/progressive-enhancement-what-it-is-and-how-to-use-it/