Google is rolling out a new mobile-first index over the coming months. The official announcement came at the beginning of November on Google's Webmaster Central Blog, although industry insiders have been speculating about the change for over a year. Google says that it is testing the mobile-first index, with the goal of switching to an index that uses the mobile version of a page’s content to serve all results. The process is still in an experimental phase, and the transition from desktop to full mobile indexing may occur slowly.
Google says that the new index is being developed in response to the way people use the web. Since more than half of all searches occur on a mobile device, Google believes it makes sense to crawl pages accordingly.
What is indexing?
Indexing is the way by which a search engine parses data, organizes it and stores it so that is easily retrievable. Google uses crawlers, most famously the Googlebot, to look at web pages and follow links to discover additional pages. During the crawling process, Google identifies the content on your pages and the structure of your website.
Google's index is where it stores the information the Googlebot has uncovered. The index contains what is essentially a copy of all crawled pages, formatted in a way that makes sense to Google's ranking algorithm. When someone performs a search, Google looks at its index to retrieve data and determine results, which is much faster and more efficient than analyzing unorganized pages across the web for every query.
Mobile vs desktop indexing
Until now, Google has served all results from its desktop index. This means that the Googlebot desktop crawler inspects the desktop version of a page and stores that version. Crawlers then look for mobile-friendly signals, and mobile results are adjusted accordingly, but a separate mobile index was not created.
In this scenario, when someone searches from any device, the results he or she sees are retrieved and ranked based on information in the desktop index. Even if the searcher is on a mobile phone, he or she sees a desktop-index-based result with a mobile-friendly marker.
This can lead to an issue that Google sees as bad user experience. Mobile pages are often stripped down versions of their desktop counterparts. Many mobile pages contain less content than desktop pages in an effort to show mobile users only the most critical information — or the website owner's best guess at what a mobile user wants to see.
When Google creates search results pages, it pulls from the desktop index to create the snippets users see on results page listings. In too many instances, the content used to create this snippet may not be available on a mobile version of the page. A searcher may click on the result from a smartphone only to find that the information he or she is looking for is not there. Google is pushing for a mobile-first web and looking for the most authoritative, useful pages to show searchers. In theory, if content is not useful enough to be on a mobile page, then perhaps that page is not the best authority on the topic of said content.
Will this affect rankings?
Understandably, many people are concerned about how the switch to a mobile-first index will affect rankings. Google claims ranking changes will be minimal.
In part, this is because the mobile-first index is not the same as a mobile-friendly ranking signal. A website can be in Google's mobile index without being mobile-friendly. Websites that are not mobile-friendly are already being docked, and the switch to a mobile-first index will have no bearing on that calculation. Mobile-friendliness signals are separate from the index.
To understand how rankings may be affected, it is instructive to look at three potential website scenarios: a responsive design, a separate mobile site and no mobile site.
Responsive design: Websites that use a responsive layout should remain largely unaffected, since the same pages and markup are being served from the same urls across devices. With a responsive layout, the mobile Googlebot will see (mostly) the same content as the desktop bot. If your site is responsive, be careful how much content you strip from the mobile layout. If necessary, hide content in tabs or drawers for a better user experience, but keep it available. Think: if the content is not important enough for a user to see it on a phone, does it need to be on a landing page at all?
Separate mobile sites: Google has been encouraging webmasters to employ responsive design over a separate mobile site for years, but until now the consequences for choosing one option over the other were either slight or non-existent. The mobile-first index changes that equation. If your site uses device type redirects or canonical tags to serve different content to a mobile site that sits on a different url (like mobile.mywebsite.com), you could see a ranking shift. This is because Google's mobile crawler will only see the mobile content and will not see any content that is exclusively on your desktop site. If the content of your mobile and desktop sites is significantly different, you could see ranking consequences.
Google says that it is working on a fix for this issue, but it still may be a good time to reevaluate your content strategy.
No mobile site: If your website is not mobile-friendly, the mobile Googlebot will still crawl your desktop site. Nothing changes here. Your site won't get the mobile-friendly tag, but that is already the case. (Don't let this serve as an excuse not to make your website mobile-friendly. It should be. As soon as possible.)
What can you do?
The switch to a mobile-first index necessitates attention to mobile optimization. Here are some things you can do make sure your pages look good to Google's mobile crawlers.
1. Up your page speed.
2. Evaluate and organize your content.
The idea behind mobile-first design is that you start with your leanest, most impressive (and most necessary) features. You then progressively enhance what is already a solid page with elements that work on larger screens. This approach forces you to pick what is most critical at the outset of a project.
Even if your website did not start with mobile-first design, now is a good time to apply that thinking to your content. What is your most helpful service or insight? What do your visitors need to see on a landing page, and what might best be shown on a subpage? If you find you have stripped a lot of content from your desktop site to accommodate mobile, your desktop pages might be unnecessarily bloated. Evaluating your content and navigation hierarchy can help align your message (and SEO goals) across all users.
3. Be mobile-friendly.
While mobile-friendliness is unrelated to the mobile-first index, it is still a must. Google is pushing for a mobile-first web, and it is only a matter of time before its algorithm starts placing more weight than it already does on mobile-friendly ranking signals. Google is upgrading its Mobile-Friendly Test Tool, and you can test drive the new version here to see how your pages score and to get suggestions for how to make improvements.
4. Use structured markup on all page versions.
Structured markup tells search engines what kind of information is contained on a page, like an address or phone number or operating hours. According to Google, if you have a responsive layout where “the primary content and markup is equivalent across mobile and desktop,” you should be fine. If you are serving different content and markup across devices, Google suggests that you make sure you have structured markup on both mobile and desktop pages.
5. Verify your mobile site in Search Console.
If you have verified your desktop site in Search Console and have a separate mobile site, be sure to add and verify it as well.
6. Don't panic.
Google's move to a mobile-first index has been both anticipated and expected. The methods already available for making your site user-friendly, mobile-friendly and well-optimized are not changing. As the new index rolls out, small tweaks may be necessary, but attention can be paid to shifts as they happen — should they happen at all. Overall, optimizing for Google's mobile-first index will provide your visitors with a better experience, which helps with both trust and conversion.