SEO Glossary

Hreflang

The HTML attribute that tells search engines which language and regional version of a page to serve. The reciprocity rule is broken in roughly 80% of audits we run.

Definition

Hreflang is an HTML attribute (rel="alternate" hreflang="...") that tells search engines which language and regional version of a page to serve users based on their location and language preferences. Introduced by Google in 2011, hreflang is the standard mechanism for managing multi-language and multi-region SEO without triggering duplicate content issues.

Hreflang lives in one of three places: HTML <head> tags, HTTP response headers, or XML sitemap entries. All three are equivalent in signal strength. Most sites use the <head> implementation for simplicity.

Syntax

<link rel="alternate" hreflang="en-us" href="https://example.com/us/page" />
<link rel="alternate" hreflang="en-gb" href="https://example.com/uk/page" />
<link rel="alternate" hreflang="de-de" href="https://example.com/de/page" />
<link rel="alternate" hreflang="x-default" href="https://example.com/page" />

The format is language-region using ISO 639-1 language codes and optionally ISO 3166-1 Alpha 2 region codes. en-us means English speakers in the United States. en alone (no region) means English speakers globally. Region without language (en-419 for Latin America) is also valid.

The x-default attribute

x-default is a special hreflang value indicating the fallback page when no other language/region match is found. Use it for:

Google explicitly recommends including x-default for any multi-region site. Without it, users in unsupported regions may see arbitrary versions.

The reciprocity rule (most-broken)

Critical: Hreflang tags must be reciprocal. If page A declares page B as its German alternate, page B must declare page A as its English (or whatever) alternate. One-way hreflang is silently ignored by Google.

This is the #1 source of broken hreflang implementations in audits. A US page lists UK, DE, FR alternates. The UK page lists only US and DE (forgets FR). FR sees no reciprocal link from UK, so the entire UK-FR pair gets dropped. Search Console flags this under "Hreflang errors" but only intermittently.

5 common mistakes

MistakeSymptomFix
Missing x-defaultUnsupported-region users see random versionAdd x-default pointing to language-selector or primary version
Non-reciprocal tagsOne-way links silently ignoredEvery page in cluster must list every other page
Using country code as languagehreflang="uk" not valid (UK is region not language)Use hreflang="en-gb" instead
Pointing to non-canonical URLHreflang ignored if URL is not canonical itselfHreflang targets must be self-canonical (rel=canonical points to themselves)
Mixing language and contentGerman hreflang on English contentHreflang must match actual page language

When you do NOT need hreflang

Verification

Two ways to verify hreflang correctness:

  1. Google Search Console → Legacy tools → International Targeting (deprecated but still functional in 2026). Shows hreflang errors and reciprocity issues per language.
  2. Screaming Frog or Sitebulb with hreflang module enabled. Crawls the site, builds the hreflang graph, flags non-reciprocal pairs and missing x-default.

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