Efforts to develop HTML5 as a replacement for HTML4 and XHTML began in 2004. Over the ensuing decade, the standard was revised and honed until it was declared completed in October 2014.
HTML5 includes a lot of changes and enhancements. Principal among them are new sectioning elements (main content, menus, headers, footers, links, articles, and sections, etc.) that make it much simpler for web developers to communicate page structure.
But what effect, if any, does it have on Google organic search?
If you ask us to bet, we’d bet that HTML5 does improve SEO. Our intuition tells us that giving Google more semantic information about how a webpage is organized certainly doesn’t seem like it could hurt a page. At worst it seems like it would be neutral, and at best it seems like it could help. Finally, we believe that having to choose which HTML5 sectioning elements to use coaxes developers into thinking about content in new ways, including examining its purpose on a very basic level and whether it’s needed at all. This closer attention to detail probably improves content architecture, which is a well-established SEO factor.
HTML5 and WordPress
Many WordPress themes use a lot of <div> tags which convey limited page structure. If search engines use HTML5 sectioning elements to better index the body of a page (as separate pieces of content), themes that don’t output HTML5 are missing the boat. HTML4 pages are treated as one section of content and opportunities to improve SEO might be squandered. We suspect that theme developers have been slow to include HTML5 tags because they question their potential to improve SEO and because browser support for the sectioning element tags has been implemented at varying paces in different browsers. Today, however, 95 percent of browsers support most if not all HTML5 tags.
It’s probably worth your while to check your theme’s output and modify it if it’s not outputting in HTML5.
To check your theme, go to a page with a lot of content and view the source. If you see only <div> tags and no <article> or <section> tags, it is probably using HTML4 and not HTML5.
You don’t have to abandon your theme just because it doesn’t output HTML5. A child theme can be developed to modify the theme so that it will output HTML5 instead of HTML4 without having to make any structural changes to the site, theme or database. Once the child theme is installed, if there are SEO benefits to be had, you’ll have them!