Hreflang
Link annotations that tell search engines which language and region each version of a page targets, so the right one is served.
Hreflang is a set of annotations — rel="alternate" hreflang link tags, or their sitemap/header equivalents — that tell search engines which language and optional region each version of a page is for. On a multilingual site they help Google serve the Spanish page to Spanish searchers and the German page to German searchers instead of picking one arbitrarily.
Hreflang has to be complete and reciprocal to work: every language version must list all the others, including an x-default for unmatched users, and each hreflang URL must be absolute and match the page's own canonical. Half-finished or one-directional annotations are commonly ignored, and pointing hreflang at pages that aren't actually translated advertises thin, machine-translated content as indexable.
A useful discipline is to only emit an hreflang alternate for a language once its translation coverage is genuinely above a quality threshold — stripping the below-threshold alternates rather than shipping them keeps a partially-translated site from being flagged as low quality.
Related terms
- Canonical Tag — A rel="canonical" link that names the preferred URL for a page, telling search engines which version to index when duplicates exist.
- Indexing — Storing a crawled page in a search engine's index so it can appear in results. Crawled is not the same as indexed.
- SEO (Search Engine Optimization) — The practice of earning more relevant traffic from search engines by making a site easier to crawl, index, understand and trust.
- XML Sitemap — A machine-readable list of the canonical, indexable URLs on a site, submitted to search engines to aid discovery.