Mobile-first indexing
Mobile-first indexing — the principle by which search evaluates the site based on its mobile version. Content that is only visible on desktop does not exist for ranking purposes. The transition is complete for all sites, and this is not a setting that can be turned off.
What follows from this
- Content must be the same. If the text on the mobile version is shorter and some blocks are hidden, the trimmed version is indexed.
- Markup must be the same. Headings, structured data, canonical addresses must be present in the mobile version.
- Images and alt texts must be in place, otherwise traffic from images is lost.
- Hidden by default text (in tabs, accordions) is indexed, but this is not a reason to hide half the page.
Common mistakes
| Error | What it leads to |
|---|---|
| Separate mobile subdomain with trimmed text | Short version is indexed, rankings drop |
| Lazy loading without a fallback | Content is not visible to the bot — see JavaScript rendering |
| Different internal links in the mobile menu | Some pages lose internal weight |
| Blocking resources in robots.txt | The bot cannot render the page |
Mobile version and speed
Mobile indexing does not mean that only speed on the phone is evaluated, but in practice, mobile metrics are almost always worse than desktop ones: weaker device and channel. Therefore, it makes sense to start speed optimization with the mobile version — see Core Web Vitals.
What it changes in promotion
Nothing regarding links and nothing regarding content — only what version of the page needs to be checked changes. Before launching a cascade, make sure that the promoted page on mobile shows the same text and links as on desktop.
Responsive or separate version
Responsive design, where the same address adapts to the screen, is simpler and more reliable than a separate mobile subdomain: there are no discrepancies in content, mutual version indications are not needed, and addresses are not duplicated. A separate mobile version today is almost always a legacy, not a solution.