What is W3C?:
W3C is a community where Member organizations and the public work together to develop Web standards, they do this because they beleive is important for everyone to have access to the web.
What is Validation?:
Web site Validation uses the standerds generated by the comunity to assist programers in cheacking their code for bugs.
When I did the self-Validation I had one mistake which I quickly fixed by deleating the aditional h3 tag in my code.