What's the level or credibility of the following towards SEO : W3C HTML Validation W3C CSS Validation W3C XHTML 1.0 Validation
Validation itself has no impact on rankings, but if your html markup makes it difficult or hinders a search engine from crawling and/or indexing a webpage then it can impact your rankings. Valid html can also affect user experience which can indirectly affect your rankings by creating higher bounce rates and slower page load times. Do not obsess over W3C validation (the Google homepage does not validate), but make sure your pages load quickly and works properly. http://glendaledesigns.com/news/103.html