Google has been pushing its “GoMo” campaign for a while, trying to get sites set up for mobile success, but today, Google posted specific recommendations for smartphone-optimized sites on its Webmaster Central blog.

Google says it supports the following configurations for sites targeting smartphones:

1. 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.

3. Sites that have a separate mobile and desktop sites.

Google Webmaster Trends analyst Pierre Far also lists two advantages of utilizing responsive web design:

1. It keeps your desktop and mobile content on a single URL, which is easier for your users to interact with, share, and link to and for Google’s algorithms to assign the indexing properties to your content.

2. Google can discover your content more efficiently as we wouldn’t need to crawl a page with the different Googlebot user agents to retrieve and index all the content.

Google “strongly” recommends using the Vary HTTP header to let its algorithms know that the content might change for different user agents. Google says it uses this as a crawling signal for Googlebot-Mobile.

The company also notes in a help center article, “Don’t block Googlebot from crawling any page assets (CSS, javascript, and images) using robots.txt or otherwise. Being able to access these external files fully will help our algorithms detect your site’s responsive web design configuration and treat it appropriately.”

Google has specific annotations for desktop and mobile URLs that it says will help its algorithms understand your site. There is a whole section about this in Google’s Building Smartphone-Optimized Sites recommendation page.

A recent study from Adobe found that website visits from tablets grew about 10 times faster than the rate of smartphones within two years of market introduction, and by over 300% in the last year. Part of the reason for this, according to the company, is that the majority of sites are not optimized for mobile, and this is reflected when users view them on smartphones. Tablets tend to handle the sites better, to where the optimization isn’t as much of a factor.

“Tablets are better for surfing than smartphones,” Adobe Digital Index Director, Austin Bankhead, told WebProNews at the time.

Perhaps if enough sites take Google’s advice, smartphone web surfing in general will be better for everyone.