In late 2016, Google began experimenting with mobile-first indexing of Search results to provide an experience that better reflects how people now use the web. A year later, Google has provided an update on the effort that is now underway for a “handful of sites.”
The switch to mobile-first indexing is due to how Google’s crawling, indexing, and ranking systems look at only the desktop version of a page’s content. Given how mobile pages are not always in parity, those searching on mobile devices might get a vastly different experience from the fully featured site that the algorithm found best for desktop viewers.
As such, mobile-first indexing will use content from the mobile version of the site to index and rank, thus improving the primary way people search for things today. Given that this shift in indexing is significant, Google started with experiments in November of 2016:
We’ll continue to carefully experiment over the coming months on a small-scale and we’ll ramp up this change when we’re confident that we have a great user experience.
Over a year later, Google notes that it is now “evaluating sites independently on their readiness for mobile-first indexing.” For a “handful of sites,” this switch has already begun and is “closely being monitored by the search team.”
Websites with responsive web design “generally don’t have to do anything,” however Google does have an updated list of tips to ensure sites are ready for mobile-first indexing:
- Make sure the mobile version of the site has the important, high-quality content. This includes text, images (with alt-attributes), and videos – in the usual crawlable and indexable formats.
- Structured data is important for indexing and search features that users love: it should be both on the mobile and desktop version of the site. Ensure URLs within the structured data are updated to the mobile version on the mobile pages.
- Metadata should be present on both versions of the site. It provides hints about the content on a page for indexing and serving. For example, make sure that titles and meta descriptions are equivalent across both versions of all pages on the site.
- No changes are necessary for interlinking with separate mobile URLs (m.-dot sites). For sites using separate mobile URLs, keep the existing link rel=canonical and link rel=alternate elements between these versions.
- Check hreflang links on separate mobile URLs. When using link rel=hreflang elements for internationalization, link between mobile and desktop URLs separately. Your mobile URLs’ hreflang should point to the other language/region versions on other mobile URLs, and similarly link desktop with other desktop URLs using hreflang link elements there.
- Ensure the servers hosting the site have enough capacity to handle potentially increased crawl rate. This doesn’t affect sites that use responsive web design and dynamic serving, only sites where the mobile version is on a separate host, such as m.example.com.