Mobile-first Indexing

Mobile-first indexing was introduced in 2018 and means that Google will consider the mobile version of a site’s content to rank pages and to understand and collect further data from a site. It is therefore important to ensure the mobile version of your site is optimised for both users and search engine crawlers. Our Hangout Notes for mobile first indexing explain these requirements, along with providing advice from Google.

Google Determines Mobile Usability Based on The Ability to Render the Page

November 26, 2019 Source

Google determines mobile usability results based on the ability to render pages in a way that matches what a user would see on their device. Sometimes they may face issues when fetching the CSS or JavaScript files and this will display a small number of issues, with regards to mobile usability, in Google Search Console. However, John advised these are usually based on temporary fluctuations in Google’s ability to fetch individual files, but it will not affect the indexing of these pages.


Google May Still Crawl Parts of a Site With Desktop Crawler

November 15, 2019 Source

Even with the shift to mobile-first indexing, Google may still crawl parts of a site with the desktop crawler. John explained that this will not impact the site as long as things are working well on mobile.


Canonical Tags Should Remain The Same Between Desktop & Mobile Sites Even With Mobile First Indexing

October 18, 2019 Source

If you have a separate m. version of your site, the canonical should remain pointing to the desktop version, despite mobile-first indexing. This is because Google will use the canonical tag to understand which of the pages belong together. Internally, Google will pick the mobile version as canonical.


Google Uses the Viewport Tag to Understand the Mobile-friendliness of a Page

October 4, 2019 Source

The viewport tag is used for scaling a page for devices, and Google will use this tag to understand whether the page is mobile-friendly or not. Google won’t automatically categorise a page as a mobile version if it has a viewport tag.


Mobile-first Readiness Classifer Will Review Content On Both Mobile & Desktop Sites

September 6, 2019 Source

With mobile-first indexing, Google will only index what it is able to crawl on the mobile version of the site, so if there is important content on the desktop version which is not available on the mobile version, this will not be indexed. The readiness classifier will be used to recognise if the content is similar enough on both, before switching to mobile-first indexing.


A Readiness Classifier & Algorithm is Used to Determine Mobile-first IndexingA Readiness Classifier & Algorithm is Used to Determine Mobile-first Indexing

September 3, 2019 Source

A readiness classifier is used to determine whether or not pages are ready for mobile-first indexing and looks at elements like internal linking, anchor text and content differences. However, if the algorithm determines that the majority of pages are ready then the site will be moved, even if some pages have content inconsistencies. This could impact rankings.


Mobile-first Indexing Isn’t a Ranking Factor or Quality Signal

September 3, 2019 Source

There’s no need to push a site to be moved to mobile-first indexing. This is only a technical change in the way pages are crawled and indexed, and being in the mobile-first index doesn’t come with any quality signals or ranking boosts.


Incorrectly Using the Vary User Agent HTTP Header Won’t Stop Site Being Moved to Mobile-first

September 3, 2019 Source

Using the Vary: User-agent HTTP header incorrectly isn’t ideal, but Googlebot will still be able to find content on the page to index and won’t be impacted much.


Having Different CMS’ & Different Configurations Across a Large Site can Delay Mobile-first Indexing

August 9, 2019 Source

If you have a large site that uses a combination of different CMS’ and front-end and back-end configurations, this can cause Google’s classifiers to determine that your site shouldn’t be switched over to mobile-first indexing. For large sites, it can be normal for a small percentage of URLs to be moved across in batches.


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