Mobile-first indexing

by | Dec 5, 2018 | Websites

During 2018, Google starting rolling out mobile-first indexing, a change that responds to the growth in mobile browsing and their efforts to reflect this.

With mobile-first indexing, Google wants to use the mobile version of your website when indexing and ranking your content.

This has implications for websites that are either not mobile-friendly or which serve the mobile version at a separate address.

The shift to mobile

The iPhone turned 10 last year, while the Samsung Galaxy will celebrate its own 10th birthday next July.

So it’s easy to forget that use of smartphones for web browsing came much later than the devices themselves. We clung on to our desktop computers for some time after.

One reason for sticking with larger monitors for so long was down to websites being slow to embrace smaller screens. Remember how frequently you had to pinch and zoom to read a web page? Thankfully that’s becoming a thing of the past.

The situation began to change as efforts were made to adapt or replicate web content for smaller screens. In May 2015, Google said more searches were made on smartphones than on larger-screen devices.

That shift towards using smartphones for searching was a significant moment, and Google saw it coming.

“If you do not have a mobile strategy, you do not have a future strategy,” Eric Schmidt, former chief executive at Google, in 2012.

But while Google felt site owners had to embrace mobile, web designers wanting to respond had choices to make.

Broadly you could take two approaches when designing for mobiles: a separate site for mobile users, or a single responsive design that would adapt to the screen.

Mobile design choices

With the separate-site approach designers could create a standalone version of the website, either at a separate m-dot ‘subdomain’ or under a sub-directory on the main site.

The main website would reside at and the mobile version at or

With this approach they could either direct users to visit the mobile version, or use code to automatically send users to the mobile version if they were using a smaller screen.

Another approach is to serve up one version of the website, using separate style instructions to suit the screen size. This takes more time to execute but is made easier with the evolution of better style rules.

At first, the advantages and disadvantages of each approach were a hot topic. Facebook, as an example, initially chose the m-dot approach before moving to a responsive design.

“Responsive design is Google’s recommended design pattern,” Mobile SEO Overview, Google Developers’ blog.

Google tells the web design community that a mobile-responsive design is the approach they favour (it’s our preferred design approach, too) and the one that works best for search engines. Today, the separate-site approach (whether m-dot or sub-directory) faces some significant disadvantages.

Firstly, you have to maintain two different versions of your website. Secondly, you need to ensure that both versions are appropriately optimised for SEO. Thirdly, separate mobile sites often have less text content and simpler navigation than fuller desktop versions, harming your SEO efforts. Finally, search engines have to identify and separately index the different versions of your site. This costs them money in crawling and indexing.

Enter mobile-first indexing…

Google mobile-first indexing

Almost three years on from reporting that mobile search had started to outnumber desktop, and after 18 months in development, Google announced in late March 2018 that they were rolling out mobile-first indexing.

With the mobile-first index, Google said it would “use the mobile version of the page for indexing and ranking, to better help our – primarily mobile – users find what they’re looking for”.

Simply put, Google aims to crawl your website as it appears on a mobile device and use this information to rank your site across all devices, including desktop.

The mobile version of your website will be seen as the primary version, and this has implications for those websites whose mobile and desktop versions are different.

Google gave the following advice for separate-site (m-dot or sub-directory) websites needing to prepare for mobile-first indexing:

“Your mobile site should contain the same content as your desktop site. If your mobile site has less content than your desktop site, you should consider updating your mobile site so that its primary content is equivalent with your desktop site. This includes text, images (with alt-attributes), and videos – in the usual crawlable and indexable formats. Metadata should be present on both versions of the site. Make sure that titles and meta descriptions are equivalent across both versions of your site.”

This has implications for websites which serve the mobile version at a separate address (m-dot or subdirectory). Separate mobile sites can often have a simpler navigation (with fewer pages receiving site-wide links). Different (and possibly slimline) content may cover topics in less depth.

Google may use this less SEO-friendly content to assess where you should rank. If your site is not mobile-friendly, it could impact negatively on your rankings, while competitors with a better mobile experience might get a boost.

Enabling mobile-first indexing

You cannot actually tell Google to treat your website as mobile-first. Rather, Google tells us they will move sites to mobile-first indexing when they are ready.

“We evaluate each site individually on its readiness for mobile-first indexing based on the best practices and transition the site when the site is ready.”

The rollout has been gradual, and is ongoing; at the time of writing many websites are yet to feel the impact. But when Google identifies your desktop and mobile versions are comparable, it should add your site to the mobile-first index.

The easiest way to know if and when your site is moved to mobile-first indexing is via Google Search Console. This is a free dashboard of website performance tools and reports, complimenting Google Analytics. If you have this set up – and you should – you’ll get a message when your site changes to mobile-first indexing.

Once your site is moved across to mobile-first indexing, you’ll probably see nothing different in the short term. But as mobile search rankings become increasingly influenced by this index, and as mobile versions of pages start to get previewed, it will matter more for your organic visibility.

Update 20/12/2018: Google have just announced hitting a major mobile-first milestone. Over 50% of the pages they display in their search results are now crawled and indexed as though from a smartphone. Their mobile-first push rolls on!

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