Through our handy Ask The Doctor service, we get a lot of e-mails asking us about HTML5′s effect on Search Engine Optimisation (SEO). While we can’t answer in great detail (Messrs Google, Yahoo, Bing, and their friends haven’t sent us in-depth details of their algorithms), we’ve rounded up some useful facts from Google, the world’s most dominant search engine.
As HTML5 gains in popularity and as we recognize specific markup elements that provide value to our indexing system, this is likely to change, but at the moment I would not assume that you would have an advantage by using HTML5 instead of older variants….
Personally, I would recommend using HTML5 where you think that it already makes sense, perhaps reverting to HTML4 if you can determine that the browser won’t support the elements of HTML5 that you use properly. While this will not result in an advantage for your content in our search results, it generally wouldn’t be disadvantageous either.
But they will take account of HTML5 once it becomes widespread, and they seem to be encouraging experimentation:
Our general strategy is to wait to see how content is marked up on the web in practice and to adapt to that. If we find that more and more content uses HTML5 markup, that this markup can give us additional information, and that it doesn’t cause problems if webmasters incorrectly use it (which is always a problem in the beginning), then over time we’ll attempt to work that into our algorithms….
HTML5 is still very much a work in progress, so it’s great to see bleeding-edge sites making use of the new possibilities :)
The Doctors’ advice on SEO is to follow Google’s time-honoured guidelines: write valid, cross-browser, accessible HTML, don’t misuse markup or “cloak” with CSS, make a site with a clear hierarchy and text links, and write good content:
Create a useful, information-rich site, and write pages that clearly and accurately describe your content.
Happy New Year. May your hat remain white.
HTML5 microdata and schema.org
Added October 2011:
Schema.org is a consortium of Bing, Google and Yahoo!. On its website it says
[schema.org] provides a collection of schemas, i.e., html tags, that webmasters can use to markup their pages in ways recognized by major search providers. Search engines including Bing, Google and Yahoo! rely on this markup to improve the display of search results
schema.org uses HTML5 microdata with new elements like
<time>. So, yes: in this special case (using these markup patterns) will ensure that this HTML5 will assist search engines to categorise your content (which is not the same as guaranteeing a higher ranking, of course).
Multiple <h1>s on a page
The new HTML5 outlining algorithm allows multiple <h1>s in a page. We get lots of questions about whether developers will be penalised by Google which, according to myth, disallowed this.
I say “myth” because Google has always allowed multiple <h1>s on a page, provided that it’s organic rather than trying to game the system, as this video shows:
However, don’t go too crazy with the <h1>-only approach as it removes any hierarchy from your pages in browsers that don’t implement the outline algorithm and screenreaders that sit on top of them.