What Google "mobile first indexing" means for SEO, and what changes from March 2021?

In March 2021, Google implements 100% mobile first indexing. Are you prepared? What all should you do to be up-to-date in terms of SEO?

Just from a knowledge point of view too, a number of queries arise: Does 'mobile first indexing' mean that Google now has two types of search bots and it maintains two types of search indexes of websites? Is mobile first indexing a sudden change? Does it impact our websites or blogs from SEO point of view? What happens to the desktop versions of websites on Google search?

What is mobile first indexing?

Mobile first indexing means this: For ranking websites and web pages for search purposes, Google (or any other search engine) gives precedence to the mobile version. When a mobile version is available, that one is assessed for indexing. 

Does Google maintain a separate index for mobile websites?

No.

Google has clarified this recently: ... there isn't a separate mobile-first index; Google Search continues to use only one index. Google Search continues to show the URL that is the most appropriate to users (whether it's a desktop or mobile URL) in Search results.

Is mobile first indexing a sudden decision by Google?

Google started taking mobile search more seriously than desktop search as early as 2016. In a blog post in that year, it announced: To make our results more useful, we've begun experiments to make our index mobile-first. Although our search index will continue to be a single index of websites and apps, our algorithms will eventually primarily use the mobile version of a site's content to rank pages from that site, to understand structured data, and to show snippets from those pages in our results. Of course, while our index will be built from mobile documents, we're going to continue to build a great search experience for all users, whether they come from mobile or desktop devices.

The experiment continued in the following years. Starting July 2019, Google started 'mobile-first' indexing on all new websites by default. It wanted to take it to all webpages by September 2020, but postponed it to March 2021 because of Covid-19 pandemic.

There is no mobile only indexing yet. But whether you like it or not, Google is forcing all website owners to move towards giving a better user experience on smartphones. Most websites that care for search traffic would have fallen or would soon fall in line; those who do not will suffer. 

Is my website or blog crawled by Google's mobile bot or desktop crawler?

Google has said that by this time, over 70% of websites are being crawled by its mobile crawler.

Go to Google Search Console and open your website/ blog. Under Settings menu, you will have information on whether your website is already being crawled by Googlebot Smartphone - which is the crawler for mobile sites (see the screenshot given here).

Why mobile first indexing?

Google says, web search is now carried out more and more on smartphones. Of all the search traffic on Google, over 60% came from mobile devices in 2020 and the number is on the rise. It is natural that to serve people who make searches on mobile phones, Google would like to rank the web pages higher if they have more value for users of these devices. 

What should a small business owner or blogger do so that his website or blog does not lose?

Google itself has come out with details on how mobile first indexing can hurt websites that have different websites for desktop and mobiles, and what the best practices are. For a layman, these could be confusing, but don't sweat; just take some actions that are given here unless your website or blog is very old highly customized (but in that case, you will hire a techie, won't you?)

So that your website or blog does not lose in terms of SEO because of Google's new search crawling norms in favor of mobile sites, you should ensure the following. 

• If you are a blogger on a progressive blogging platform (including Wordpress and Blogger) or your site is mobile-ready by design (it does not have a separate mobile site), you need not take a major action. 
• Have a mobile version (in addition to the normal website). Modern themes/ templates on blogging platforms and website builders have this as a default feature. If you are not sure, you can check your website by typing the URL of your website or any of its webpages on web browser and adding ?m=1 at the end like this:

www.example.com >> www.example.com?m=1

• Ensure that the mobile site has the same content as your desktop version, otherwise some of your content will not be indexed by Google. Since the mobile version has to be mobile-friendly, some information is presented in a different way and some is hidden or not displayed at all. For example, the top menus of the desktop versions may disappear altogether. That is all right if your users on mobile phones do not lose in terms of navigation, engagement, etc, but the website would lose in terms of SEO if the mobile version is deficient. 

Therefore, look closely how the website renders on desktop, tablet and mobile versions. If the menus and sidebar of the desktop version disappear altogether in the thinner versions, you are losing big in terms of discovery of content by visitors. On many website/ blog themes, developers have taken care to give placeholders for hidden menus (in the form of dots or lines) or adjusted the menus on top or bottom of the screen. However, when that is not provided (old theme not updated for mobile-friendliness), one must manually place the menus by tweaking the code for the mobile version. (On Wordpress and Blogger, the code of the theme has to be changed where mobile version's features are coded.)

• Also check whether the mobile version is as good in terms of user experience. If the mobile version has all the content that is available on the desktop version but the text is rendered in small size and is unreadable, or the speed is slow or a popup covers the entire screen and does not show how to close it, it will have a very bad impact on the ranking of the website though the desktop version might look fantastic.
• Related to the above is to ensure that you have not made manual changes to the site in a way that they will not automatically apply to the mobile site. For example, if you have marked some internal webpages as noindex or nofollow, they might not apply to the mobile version. 
• Have the metadata about the website same on both the versions.

If your website or blog needs a big change, look at the detailed technical details on the mobile-first indexing best practices page on Google (link given in the previous para). 

Take note that mobile-friendliness has to do with display as well as other features. Though Google has not directly told it anywhere, webmasters should also think of changes in the content so that the webpages are mobile-friendly. For example, 

• Since it is not easy to read long chunks of text on mobile devices, shorter posts give a better user experience. So, it would be better to break long posts into a series of posts.
• Images pose a problem when their width is not set in percentage terms or responsive for different device widths. But they have another problem when they are squeezed to fit the width of the smartphone: things become smaller, and embedded text can become unreadable. So, it will help to edit images having embedded text, keeping smartphones in mind.

With mobile first indexing, does Google show mobile version on desktop search?

Google tries to show you the web pages that render the best on your device. It will show you the mobile version of search results on the mobile device and desktop versions on desktops and laptops. 

So that the version that shows up and that is indexed do not confuse you, let me show how mobile-first indexing works, with this example: 

Earlier Top Blogs (the blog that you are reading) used to be crawled by the legacy crawler but it is now being indexed by its smartphone crawler. The display of the website and its web pages happens to be exactly the same as earlier: a 2-column display on laptops and a single-column display on smartphones.

What has changed it like this: The desktop version of a web page (e.g this relevant page on search engine optimization: What is SEO) was ranking based on Google's ranking parameters, say with a value x. Now, the smartphone crawler does not crawl this web page but its mobile version and may rank it higher or lower than x depending on its ranking parameters.