What are the Core Google Guidelines on Mobile?

How mobile‑friendliness and mobile‑first indexing impact Google search rankings.

Search engine optimization (SEO) is different for mobile devices than desktops. Mobile SEO requires a separate strategy because it’s impacted by variables like screen size, location, and operating system. Google provides some of the most important guidelines for mobile SEO so businesses can rank well no matter where or how someone searches.

Google’s guidelines emphasize mobile-friendliness and mobile-first indexing. These are both concepts related to specific updates that Google launched, and knowing what they entail is key for mobile SEO.

Mobile-friendliness

For many years, websites were built with mobile content on its own subdomain. But this created lots of problems for both the people using and building the sites. In time, Google recommended solutions that enabled people to host content that worked across devices, and for users to access that content seamlessly. Since the 2014 Mobile-Friendliness Update, Google rewards websites that meet certain criteria that make websites easy to use on mobile devices.

Responsive design

  • Google recommends that developers build 1 version of a site that can rearrange itself to fit well on different screen sizes—a concept called responsive design. Using this principle, websites format differently on devices of all sizes, so that users find essentially the same page, but the navigation may move or collapse for more efficient use of space on a smaller screen. It can also mean that images are coded in a way that they shrink appropriately for the screen being used to ensure a good experience. (To test mobile-friendliness and rank sites for search, Google usually crawls as an iPhone 9 or an Android Nexus X5, but this is variable and changes over time.)

Page content

  • Beyond being built with responsive design, the Mobile-Friendliness Update requires that text and buttons (called tap-targets) be large enough to read and easily click on mobile. It also says that the page can’t require sideways scrolling (an indication that the page is either not built in responsive design or that the page sizing or viewport is not set correctly) and that on-page text has sufficient contrast from background colors.

Interstitials

  • The update also limited the ability of mobile sites to show interstitials. Sometimes called modals, interstitials were on-page pop-ups that didn’t open a new window, but instead covered content on the page until a button was clicked. Most often the button was a link to the app stores, to encourage users to download the company’s app, which at the time, tended to offer a better mobile experience than the website. Google felt that these interstitials hurt the user experience, but they also made the page hard for Google to crawl, because they used JavaScript to block content. Up to this point, Google had always ignored or struggled to crawl JavaScript, thus they had a vested interest in keeping people on the web rather than in apps.

Page speed

  • The final requirement for mobile-friendliness is about page speed. Pages must load at a reasonable speed on mobile—despite often having slower data networks and loading content differently than desktop browsers. This is something to consider when building a responsive design because added JavaScript can make both the desktop and the mobile load time slower. Google PageSpeed Insights can help you sort out the cause of load time problems on mobile devices.

To see how your page stacks up to these requirements, Google offers a Mobile-Friendliness Test. You can also check out how your mobile pages look on different devices with the free MobileMoxie Page-oscope.

Mobile-first indexing

Google now uses mobile-first indexing, which means that they index and rank websites based on the mobile version. Desktop-specific content is still indexed, but secondarily. This means businesses should make sure that content on their mobile site, or the mobile view of the responsive design version of their site (sometimes called mobile rendering), includes the same SEO elements that drive rankings from the desktop site.

Here are the main things that Google focuses on when matching between the mobile version and the desktop version of the site:

Matching metadata

  • Metadata generally includes the HTML title tag and meta description, but can also include alt text associated with images, and a few other things that are visible only in the code. These elements should include important keywords for the page—the ones you would like to rank for—but they also should be informative and useful, because they are often displayed directly in the search result with your ranking. To make sure that Google doesn’t miss out on critical SEO information when they crawl the mobile view of a site, the mobile and desktop metadata should be the same. This is easy in responsive design, but it can be a bit more complicated if they are separate pages.
  • Google uses internal links to understand the structure of your website. If different links are included in the mobile version or mobile rendering of the website, then Google will understand it differently. This can be a problem for both responsive design sites and separate mobile sites. On responsive design sites, less critical information is often collapsed or hidden to make the narrower, smaller pages easier to navigate. When separate mobile and desktop sites are at play, sites often include entirely different navigation and links. A good way to learn about your internal link structure is a tool like Sitebulb, which helps you visualize what pages are linking to each other pages. Other software like Screaming Frog and DeepCrawl can also provide the same information, though in a somewhat less visual way. Using any of these tools, it is important to crawl the site twice; once emulating Google’s desktop crawler, and another time using Google’s mobile crawler. (The best way to do it is using the text only or AJAX crawling scheme, if it is available, because this will be the most strict interpretation or guess, regarding what links Google will be able to see and what links they will not.)

Matching schema

  • Google also checks for matching tags, or schema, on mobile versions of a site. This helps the search engines understand and classify the contents of a page by making on-page data more machine-readable, which is great for search engine crawlers. Google looks for the types of schema that they officially recognize, or plan to support, to match on the mobile and desktop site. You can compare your mobile and desktop schema using Google’s Rich Results Test, if the page is mostly HTML, or the URL Inspection Tool, which is better at JavaScript-heavy pages. The URL Inspection Tool is part of the Google Search Console, Google’s free SEO and website health tracking platform. Google Search Console allows users to get bulk information about how mobile-friendly a website’s pages are, and also the ability to use the URL Inspection tool. It will let you know if there are any problems with the page that need to be fixed for Google to index and rank the page.

Matching hreflang

  • Google wants businesses to ensure hreflang tagging is crawlable on both mobile and desktop sites. This attribute is included in the HTML tag, and it helps Google by linking to translated versions of the page so Google can try to serve those versions of the page when they are appropriate. Recent changes in Google are very focused on translatability, with the goal of understanding and serving the right translation of a page for the user.

Google’s recommendations for mobile websites have evolved over the years and they will continue to change. Mobile-friendliness and mobile-first indexing both changed SEO in a big way across devices, and for now, they are the keys to success. Moving forward, it’s important for businesses to pay attention to all of Google’s announcements and to test and track mobile search results as you implement and update your strategy.

Written by Cindy Krum for Mailchimp. Cindy is an expert in mobile SEO features.