Google first announced this term “Mobile-first Indexing” on 04 November 2016 in his Official Blog post. In this post, they reveal about experimenting on its indexing process due to technology enhancement as people are shifting from desktop to mobile. So, what it is all about? Let me explain it from the basics.

How search engines work?

I know it’s a very basic question, but before understanding Google’s new indexing process we need to know beginning. So, it is a three steps process explained below:

Crawling

It is a process in which Google’s web spider or Googlebot visit every website generated from previous crawl process. Google bot evaluates and learns about web pages by analyzing Meta data and keywords.

Indexing

Google bot processes all web pages as per the information it gets in crawling process and indexes them in such a way that helps in ranking.

Retrieval and Ranking

When user searches any query, it searches the index and find the most relevant results on the basis of certain factors like words appear in title, page includes synonyms, quality of website and many more.

So, how above process helps us to understand the Mobile First Indexing? As name suggested, Google is experimenting with indexing process to improve user experience.

What exactly is Mobile First Indexing?

According to Google’s statement:

“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.”

Let me explain it in more simple words:

Previously, Google works on desktop index that created by Googlebot desktop crawler. It shows results and snippet based on desktop index.

So, how it causes problem?

There are many cases where user didn’t get right results like redirection to mobile site, things shows in snippets not available on mobile version of website etc.

Now, Google has started to use the mobile version of the web as their primary search engine index. In other words, Googlebot-mobile crawls the websites first and based on mobile index, Google retrieve results.

Business owners who have responsive website and those don’t have mobile site are safe as Google says:

• If you have a responsive site or a dynamic serving site where the primary content and markup is equivalent across mobile and desktop, you shouldn’t have to change anything.
• If you only have a desktop site, we’ll continue to index your desktop site just fine, even if we’re using a mobile user agent to view your site.

However, If you have a mobile site, but content and markup on both web and desktop is different need to fix few things suggested by Google:

• Make sure to serve structured markup for both the desktop and mobile version.
• Use the robots.txt testing tool to verify that your mobile version is accessible to Googlebot.

For more queries, please visit these links:

https://webmasters.googleblog.com/2016/11/mobile-first-indexing.html

http://searchengineland.com/faq-google-mobile-first-index-262751

Also, if you still find any difficulty to understand it, feel free to ask your query in comment section!