International SEO is about disambiguation: telling engines which version of a page is meant for which language and region, so a French user gets the French page and a US user gets the US one. The mechanics — hreflang, the lang attribute, country targeting, consistent URL structure — are easy to get subtly wrong, and the failure mode is quiet: the wrong version ranks, or your localized pages cannibalize each other.
This category only applies to multilingual or multi-region sites; single-locale sites can largely skip it. Each check has a stable ID (I1–I5). Two are core; the rest are extended.
The <html lang="…"> attribute states the primary language of the page — lang="en", lang="fr", lang="es-MX". It's a small but foundational signal: browsers use it for translation prompts and hyphenation, screen readers use it to choose the correct pronunciation, and engines use it to confirm the content language.
It must be present and accurate — a page of Spanish content declaring lang="en" sends a contradictory signal. On multilingual sites, each localized page should declare its own language.
It's a one-line fix that's frequently missing or copy-pasted incorrectly from a template, so it's worth checking even on otherwise polished sites.
hreflang annotations map your page variants to languages and regions: hreflang="en-us", hreflang="fr", hreflang="x-default", and so on. They tell search engines, "for a user in this language/region, serve this URL." Done right, the French page ranks for French users and the US page for US users, instead of the wrong one showing up.
The two cardinal rules: hreflang must be reciprocal (if page A points to B as its French version, B must point back to A), and it must use valid language/region codes (ISO language and country codes). A non-reciprocal or mistyped hreflang cluster is silently ignored — the most common international SEO bug.
Include an x-default for the fallback version, and place hreflang consistently (all in the HTML head, or all in the sitemap — don't mix). When it works, it's the single most powerful tool for preventing duplicate-content and wrong-language problems across locales.
Extended checks
Diagnostic checks flagged for review — useful polish, but they don't carry the same score weight as the core checks above.
Country targeting combines several signals: a country-code domain (.de, .fr), hreflang regional codes, server/hosting location, on-page language and currency, and local contact details. The strongest is the domain — a ccTLD is an unambiguous signal — but generic domains can target effectively when other signals align.
The failure mode is conflict: a German ccTLD serving English content with US pricing from a US server sends a mixed message and weakens targeting. Pick a structure and reinforce it consistently.
Localisation goes beyond translation: it uses idiomatic phrasing, correct currency/units/date formats, and examples and references that resonate with the local market. Native users (and quality systems) can tell the difference between content built for them and content merely converted into their language.
Thin, auto-translated pages are exactly the kind of low-value content that quality systems increasingly discount. Localise properly — ideally with native speakers — rather than relying on raw machine output.
Good translation is fluent, accurate, idiomatic and appropriate in tone — it effectively disappears, letting the content speak naturally. Poor translation constantly reminds the reader it's a converted copy, with stilted phrasing, literal idioms and grammatical slips.
Machine translation isn't forbidden, but publishing its raw output is the problem. Use it as a draft and have native speakers or professional translators refine it into natural, accurate content.
Why international signals matter for SEO and GEO
For a single-language, single-country site, this category is largely moot. But the moment you serve more than one language or region, getting it wrong is costly and quiet: the wrong-language page ranks, your translations compete against each other as duplicates, and users bounce off a snippet they can't read. Hreflang and a correct lang attribute are the disambiguation layer that prevents all of that.
The effort also compounds with the rest of your SEO — every localized page that's properly declared, fully translated and cleanly structured is a page that can rank and convert in its own market. Half-measures (translated body, English metadata; non-reciprocal hreflang) tend to deliver none of the upside.
AI answer engines serve users in their own language, so the same disambiguation that helps search helps GEO: a correct lang attribute, valid hreflang and fully localized content let an engine confidently match the right-language version of your page to a query — and quote it — instead of surfacing a mismatched or half-translated version, or skipping it for lack of clear language signals.
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<html lang> attribute.