W3C COMPLIANCE FOR INTERNATIONAL WEB STANDARDS
W3C validation is the process of checking a websites code to determine if it follows the formatting standards. If you fail to validate the pages of your website based on W3C standards, your website will most likely suffer from errors or poor traffic owing to poor formatting and readability.
W3C validation helps you to get better rankings in search engines. Errors in your code can affect your sites performance and make a big impact on your sites SEO, search engines check the HTML or XHTML code of your website when searching. If they find invalid HTML or XHTML code – meaning code that does not follow the official rules, you might be removed from their indexes. If there is an error on your web page code, robots will stop searching your whole websites content.