Mobile SEO is a confusing space. As mobile devices increasingly dominate the web, webmasters and marketers have often rushed to create mobile-friendly websites. In this rush, SEO best practices are often ignored in favor of rapid deployment.

However, search is a key channel for reaching mobile users, and brands are now having to look back and evaluate their mobile websites from an SEO perspective. Fortunately, Google has recently released an updated set of mobile SEO guidelines that will help marketers and developers understand and implement solid mobile SEO.

The Mobile SEO Debate: Single URL vs. Mobile URLs

One major issue that has dominated the mobile SEO discussion for years is – should mobile sites be built on unique mobile URLs, like mobile.mysite.com, or should mobile sites use responsive design to serve mobile content and desktop content under the same URL?

Google has finally weighed in on the issue with a clear guideline – “Google Supports…sites that use responsive web design, i.e. sites that serve all devices on the same set of URLs, with each URL serving the same HTML to all devices and using just CSS to change how the page is rendered on the device. This is Google’s recommended configuration.”

Basically this means that webmasters should attempt to develop websites that serve the same actual content to both desktop and mobile devices, and simply use CSS to restyle mobile content for usability. This is the simplest and most Google-friendly method of serving mobile web content.

Other Options for Mobile SEO

While Google has come out in favor of responsive design, that doesn’t mean it’s the only option. Google supports other options, including -

• Sites that dynamically serve all devices on the same set of URLs, but each URL serves different HTML (and CSS) depending on whether the user-agent is a desktop or a mobile device.

• Sites that have separate mobile and desktop URLs.

So while Google prefers responsive design, sites that are already using mobile URLs don’t necessarily have to rebuild their entire mobile sites. In fact, as Bryson Meunier covers in a recent Search Engine Land article, Google might generally prefer responsive design, but not at the expense of user experience.

Finally, some marketers might be confused on the difference between responsive design and dynamic HTML serving.  Responsive design only impacts the CSS of a page – the actual HTML remains identical. By contrast, dynamic serving allows for the HTML content and CSS stylesheet of a page to change based on a user’s device, even though the URL of the page remains the same.

More Mobile SEO Notes

One interesting feature that Google is now supporting is something called “Switchboard Tags.” For websites that need to keep mobile-unique URLs, webmasters can now specifically send signals to Google to help identify mobile websites from desktop content.

The tags work like this: on desktop pages, webmasters add a link rel=”alternate” that points to corresponding mobile URLs. On the mobile versions, webmasters add a standard rel=”canonical” tag that points to the desktop version. This two-way relationship helps Google discover and understand the relationship between desktop and mobile pages.

Other Mobile SEO notes to be aware of include -

• Optimization beyond responsive design. Simply restyling desktop pages isn’t a complete mobile SEO solution. Other things to optimize include efficiently resizing images to minimize load time, consolidating external files and stylesheets, and limiting the use of JavaScript libraries.

• Mobile SEO for Bing. Bing is actually ahead of Google, having come out in favor of responsive design months ago. Since Bing powers Yahoo’s organic results as well, this means that responsive design is the best practice for all 3 major engines.

• Stay Away from Robots.txt Blocks. Google has now officially said that there’s no reason to use robots.txt to block mobile sites from crawlers. This has always been a bit of a tricky strategy, but now it’s officially unnecessary.