Canonical Tag

An HTML link element that tells search engines which URL is the authoritative version when near-duplicate content exists. Prevents duplicate indexing and consolidates ranking signals.

Without canonical tags, link equity gets split across duplicate pages (?utm_source=... variants, http vs https, www vs non-www). Set a self-referencing canonical on every page; for syndicated content, point the canonical at the original source.

Real-world example

An e-commerce site has product pages accessible at both /product/blue-widget and /product/blue-widget?color=blue. Without canonicals, Google and AI crawlers index both — splitting authority. With a canonical pointing both to /product/blue-widget, all ranking signals consolidate on the preferred URL.

Frequently asked questions

Should every page have a canonical tag?+
Yes — every page should have a self-referencing canonical tag even if there are no duplicates. It serves as an explicit signal to crawlers about the preferred URL and prevents future duplicate issues from UTM parameters, session IDs, or pagination variants. It takes 5 minutes to implement site-wide.

Related terms

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