# Mobile-first indexing

> Google indexes and ranks the mobile version of a page, crawled with its smartphone agent. Responsive design avoids mismatches because both versions share the same HTML. With dynamic serving or separate mobile URLs, the mobile version needs the same content, headings, robots meta tags, structured data and metadata as desktop, without hiding primary content behind interaction.

- URL: https://geo.casa/crawling-indexing/mobile-first-indexing/
- Reference · Officially documented
- Reviewed: 2026-10-26

## What it is

> **Officially documented:**
> "Google uses the mobile version of a site's content, crawled with the smartphone agent, for indexing and ranking. This is called mobile-first indexing." A mobile version isn't required to be included in results, but Google very strongly recommends one.
>
> Sources: [Google Search Central: Mobile site and mobile-first indexing best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing)

## Responsive design avoids the problem

> **Officially documented:**
> Of the three configurations (responsive design, dynamic serving, separate URLs), "Google recommends Responsive Web Design because it's the easiest design pattern to implement and maintain." The rest of Google's guidance applies only to dynamic serving and separate URLs. With responsive design, the content and metadata are the same on both.
>
> Sources: [Google Search Central: Mobile site and mobile-first indexing best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing)

## If mobile and desktop differ

> **Officially documented:**
> "Make sure that your mobile site contains the same content as your desktop site." Moving content into accordions or tabs on mobile is fine. If the mobile page deliberately has less content, expect some traffic loss, because Google indexes the site from its mobile version.
>
> Sources: [Google Search Central: Mobile site and mobile-first indexing best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing)

> **Officially documented:**
> "Use the same robots meta tags on the mobile and desktop site." A different tag on mobile, especially `noindex` or `nofollow`, can stop Google from crawling and indexing the page. Google also won't load content that needs a user interaction, such as swiping, clicking or typing, to appear.
>
> Sources: [Google Search Central: Mobile site and mobile-first indexing best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing)

Also keep these equivalent across both versions:

- headings;
- structured data, with URLs pointing at the mobile URLs;
- the title element and meta description;
- image alt text, and ideally the same image URLs, to avoid a temporary image traffic loss.

## Separate mobile URLs (m-dot)

> **Officially documented:**
> Serve the same error status on both sites. If the mobile version of a page is an error page, "this page will be missing from the index." Avoid URL fragments (`#`) in mobile URLs, because they are usually not indexable.
>
> Sources: [Google Search Central: Mobile site and mobile-first indexing best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing)

## For AI search

To appear as a link in Google's AI features, a page must be indexed and eligible to show with a snippet ([Google AI Overviews](https://geo.casa/ai-search/google-ai-overviews/)). Indexing uses the mobile version, so content missing on mobile is missing there too. Other AI crawlers fetch pages with their own user-agents and may receive the desktop version. Responsive design keeps every crawler on the same HTML.

## Sources

- [Google Search Central: Mobile site and mobile-first indexing best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing)