HTML Validation
The recent video posting by Matt Cutts on the issue of whether HTML validation affects SERPS has once again sparked this old thread of discussion over various search engine optimisation forums and blogs. Matt Cutts has categorically stated that Google does not “give any sort of boost to web pages that validate.”
While having compliant code doesn’t give a boost to search engine optimisation, removal of excess and unnecessary code can influence your SERPS by increasing your code to content ratio, there are a number of sites out there with excessive mark-up, making a site slow and unfriendly. So although you might not receive a listing boost it’s still a good idea to make sure your code validates as it could reduce loading time and if in the future Search Engines decide that W3C compliant sites receive a boost, any site that is compliant will be ahead of the game.
HTML validation is not integral to search engine optimisation however fast loading pages and a low code to content ratio is much more important as this lowers how long a search engine bot spends reading a page and therefore increases how many pages the bot get to read and hopefully increases the number of pages, from a site, that the search engine indexes.
HTML Tags
Certain HTML tags can have a heavy load on a search engine’s journey through a site’s source [deprecated tags, table tags] which in themselves don’t equate to minus points in SERPs but can increase the weight and processing of the visiting search engines. If this becomes a long process then the danger is that they go away and revisit another time, indexing thus becomes hindered, so indirectly this could be a potential factor to search positions.
Compliant HTML tags are required for one thing, if there is a DTD (document type declaration) then the correct html rules (in syntax) have to apply, else the discrepancy can be picked up on, potentially hindering the site. Even if sites do not attain full w3c compliancy they don’t necessarily get big marks against them in search, unless there is another critical issue.
In line with what Matt Cutts said, historically sites with unbalanced HTML tags will still rank. In our experience sites with 20 + or 40 + warnings regarding their HTML tags can still achieve page one listings. However for the purposes of smooth search analyses and in the eventuality that search engines start to lean toward W3 compliancy in the future, HTML tags do play an indirect part in SERPs.
Website Optimiser
It is highly unlikely that HTML validation will be a factor, as Google’s own tool forces you to put unbalanced HTML tags in your web pages. The optimizer requests that you put a lot of code in the page to be tested. Most of this is fine as it’s just like the standard tracking code (i.e. lumps of Javascript spread liberally around the page) but around the section to be tested you have to put two lines of code:
One is <script>utmx_section(‘name’)</script> which is fine as it’s all balanced, but the second line is simply </noscript> which definitely isn’t.
They even go so far as to say that if your CMS/page generation system won’t let you generate an unbalanced tag. The Website Optimiser support resource states, “It will cause a problem, however, if your CMS doesn’t accept unbalanced tags. There is no current Website Optimiser workaround for this situation.”
Search Engine Optimisation
Google have been dismissive of HTML validation like many other historically ambiguous areas of search engine optimisation. Matt Cutts has spoken about keywords in the URLs and domain registration dates this year, giving a similar response on all counts. Although we have to agree that none of these factors are integral to search engine optimisation, our research shows they do have some relevancy.
The statement that HTML validation has no relevancy to SERPs is misleading to a budding webmaster as extreme cases of bad code to content ratio can lead to being penalised by Google and the speed and accuracy of which a site is indexed plays a role in SERPs which can be adversely affected by imbalanced HTML.
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With the inconsistencies between the browsers, I can understand why Google doesn’t rate valid HTML pages as being better. But I can see why being as compliant as possible can help a site get indexed better. So no matter what HTML version you decide to use, you should try and be compliant. Hopefully this will make people build better sites. :)