I have heard this over and over by various bloggers and present day SEO experts. Although many oldschool SEO practitioners have a strong affinity in the belief that W3C validating, compliant HTML or XHTML and CSS helps a lot in the ranking algorithm. Now is there any truth to this?
The premise behind the belief that valid XHTML helps in search engine ranking
Every webpage is written in the base language HTML. And this language is interpreted by web browsers. How it should be interpreted are based on rules set by the World Wide Web Consortium or W3C. Web browser makers should create browsers that follow these rules so a webpage is displayed properly.
Search engine spiders reads the content of webpages and should extract the contents of a page. Since search engines will read the code as well, then it should make sense that your site follows the code standards to make sure search engines read the code well to avoid any errors in the interpretation of the site code and the content.
Based on observation, is valid XHTML code important in SEO?
Based on personal experience, my answer would be no. I have seen many sites ranking so high with tons of validation errors. And also I have seen many sites no errors, and you get the green bar on W3C’s validation service and yet they are not ranking anywhere. If ever there is any benefit, it is not a major one and can be influenced by other factors. Although there are also other people stating that they see better ranking with valid code.
And when Vanessa Fox used to still work for Google’s Sitemap Team, in an interview with SEOMoz‘ Rand Fishkin for WebProNews, Vanessa clarified that the code is simply separate from the content right away.
But I still like W3C Valid Code
Just because there is no real benefit, I still like W3C valid code. For me it is like an addiction. I love to see the green bar on my XHTML Validation and CSS Validation. Having the green bar makes sure you are following all the rules correctly and web browsers are required to follow these rules. This makes your designs more scalable and future-proof for the years to come.
And by the way, there is still some hidden SEO benefit in valid code. But I can’t tell you because if I do, then it is no longer hidden. 
Go figure.
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I was always thinking that w3c was very important to get good ranks.
this is a very interesting concept.
Goodluck co-pinoy!
i am newbie in seo. i thought w3c valid code is one of the ranking factor of search engine, especially the google. well, thanks to this article post.
@Dilson: If you have a strong feeling that is true, feel free to believe in what you see is true for you. In SEO, everyone has different experiences. I know people that love W3C validation and feels so much positive it works better for SEO.
Google Webmaster Tools pointed out some secondary reasons for validation or cleaning up html that is useful. ( http://groups.google.com/group/Google_Webmaster_Help/web/faqs-for-crawling-indexing-and-ranking-2#valid-code)A company might not want to link to you if you are not validated or your code is not clean. As an SEO expert I know it doesn’t influence the algorythms but IT departments may have standards to follow. I also think that looking through the html for problems is important. If the site use frames or other html that is problematic code then it should be recommended to change it because it will affect the SEO program. But that’s the extent I think we need to go. I agree that W3C Validation is not a necessary SEO deliverable. Let’s do away with it
Couldn’t agree more. I also have several clients with sites that validate poorly, with detrimental affect on ranking. There are no doubt benefits to W3C compliance, but it is sometimes hard to justify the cost in light of the benefits.
wow
benj i agree. one of my sites are coded badly in HTML and CSS but still im holding the top 10 positions for 8 months now…
wow congrats!!! i love VALID XHTML sites!!!
If this really is true it will save alot of time for us.
The Web sites must be always validated against W3C standards regardless of the SEO effect, because such sort of programming style indicates about the professional approach used in the Web design company and skills of the team in particular. The output generated will look greater in all browsers and this benefits the end users as well.
Why are we only discussing about XHTML? Is HTML not supposed to be validated? We have a site http://www.webxlent.com which is written in HTML and is validated. I think validation is important for any kind of website. I have personally seen issues in performance on rendering of pages when the HTML is not validated or when we put elements in an incorrect order.
Great article! I always wondered if W3C was important to SEO and result placement. You have eased my mind
Thanks!