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Mobile-first indexing
Google primarily indexes the mobile version of your site with Googlebot Smartphone. Here is what that means in practice, and how to avoid getting caught out.
What it is
Mobile-first indexing means Google primarily crawls and indexes the mobile version of your pages, using Googlebot Smartphone rather than the desktop crawler. The content Google sees, evaluates, and ranks is the content your mobile visitors see.
This is not a future plan. It is how Google works now, and has for years. Per Google's Googlebot documentation, the smartphone crawler is the primary one. Your desktop layout might look great, but if the mobile version hides text, drops sections, or fails to load, that is the version Google judges you on.
Why it matters
If your mobile pages serve less content than desktop, you are quietly handing Google a weaker version of your site. Common traps: text collapsed behind tabs that never render, images and structured data missing on mobile, or a separate mobile URL with thinner copy.
The fix is parity. Make sure your mobile pages contain the same main content, headings, and metadata as desktop, and that Google can fetch the same CSS and JavaScript a real phone would. This last point bites sites that render content client-side, which is why JavaScript SEO deserves a close look. Responsive design usually solves all of this in one move, because there is only ever one version to keep right.
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