Canonical URL
The preferred, authoritative URL for a page when multiple URLs point to the same or similar content.
Definition
A canonical URL is the single URL that a publisher designates as the authoritative version of a page. It is declared with <link rel="canonical" href="https://example.com/page" /> in the HTML <head> (or via HTTP headers). Crawlers and agents use it to avoid duplicate-content confusion when the same content is reachable via different URLs (parameters, www vs non-www, pagination, syndication).
Relevance to GEO
AI crawlers and RAG indexers benefit from a single canonical URL per logical page: it clarifies which URL to store, cite, and return in answers. Always set canonicals on paginated, parameterized, or multi-domain variants.