Web standards hold the key to accessible, cost-effective web design and development, but you wouldn't know it from surveying most big commercial sites. In this chapter, CSS guru Jeffrey Zeldman explores some of the reasons web standards have not yet been incorporated into the normative practice of all design shops and in-house web divisions, and are not yet obligatory components of every site plan or request for proposal. If you need help selling standards to your colleagues, this chapter is for you.
http://www.peachpit.com/articles/article.aspx?p=608636
It is from the book:
Designing with Web Standards, 2nd Edition
By Jeffrey Zeldman
ISBN13: 9780321385550
ISBN: 0321385551
BINC: 8201406
Some more info:http://my.opera.com/downloadthefuture/blog/show.dml/2803182?cid=656503
Web page validator:http://validator.w3.org/check
3rd edition is out