In short. hreflang associates alternate page URLs with their intended language and optional region.

Definition: hreflang is an annotation that identifies language or regional versions of the same web content. It associates an alternate page URL with its intended language and, optionally, region.

Key facts

As of 17 October 2026, Google documents the following rules:

Google's localized versions documentation accepts annotations in HTML, HTTP response headers or an XML sitemap, and treats these methods as equivalent.
Google's multilingual site guidance recommends separate URLs for each language version and hreflang annotations to help Search link to the appropriate version.
Google's AI features documentation states that a supporting page in AI Overviews or AI Mode must be indexed and eligible to appear in Google Search with a snippet.

How does an HTML implementation work?

Google's HTML instructions place link elements inside the page's head. Each language version lists itself and the other versions. Every page carries the same set of annotations, with fully qualified URLs that include https:// or http://.

This example reproduces the annotations from Google's fictional Widgets site:

<head>
  <title>Widgets, Inc</title>
  <link rel="alternate" hreflang="en-GB"
       href="https://en-gb.example.com/page.html" />
  <link rel="alternate" hreflang="en-US"
       href="https://en-us.example.com/page.html" />
  <link rel="alternate" hreflang="en"
       href="https://en.example.com/page.html" />
  <link rel="alternate" hreflang="de"
       href="https://de.example.com/page.html" />
  <link rel="alternate" hreflang="x-default"
       href="https://www.example.com/" />
</head>

Here, en-GB identifies English for users in the UK, while en covers English without a regional restriction. The reserved value x-default identifies the fallback page for unmatched language settings. In Google's example, that page offers language and region selectors.

The same documentation supports HTTP Link headers for files such as PDFs. For sitemap implementations, each URL entry includes xhtml:link elements identifying every alternate version, including itself. Google states that using all the methods together adds no Search benefit and makes maintenance harder.

Which implementation errors matter?

Google's troubleshooting guidance highlights missing return links. If a German page identifies an English alternate, the English page must identify the German page in return. Google ignores annotations between pages that fail this reciprocal relationship.

The language code comes first; a region code alone is invalid. Google documents en-GB for English in the UK. It lists UK, EU and UN as region codes that have no effect in these annotations. An implementation review therefore checks the code values, complete URLs and return links on each variant. For HTML, the same guidance recommends validating the rendered page to confirm that the annotations sit inside a well-formed head.

How does hreflang relate to AI search?

Google's AI features guidance says that existing search engine optimization practices remain relevant to AI Overviews and AI Mode. It requires no additional technical markup for those features. For a multilingual website, hreflang has the documented role of identifying localized alternatives in Search; these sources provide no measured citation effect for AI assistants.

Page language also depends on content. Google's multilingual site guidance says it determines language from visible text. It recommends a single language for the content and navigation on each page, and links that let visitors choose another language version.

FAQ

Does hreflang tell Google which language a page contains?

Google's localized versions documentation says its algorithms determine page language without using hreflang or the HTML lang attribute. Use hreflang to identify the intended language and region of alternate URLs.

Can alternate versions use different domains?

Yes. The same documentation permits alternate URLs on different domains, provided the annotations use complete URLs and the pages link back to each other.

Should you redirect visitors automatically by language?

Google's multilingual site guidance recommends avoiding automatic redirects between language versions because they can prevent visitors and search engines from viewing all versions. It suggests hyperlinks that let visitors select a language.

Sources

Check how a page reads to answer engines. Open the GEO score analyzer