Canonical tags for duplicate content
A canonical tag nominates a preferred URL among duplicate or very similar pages. It leaves the duplicate accessible. Google can choose another URL.
Does the duplicate still need to exist?
| Situation | Starting point |
|---|---|
| Tracking URL with the same content | Keep the URL if needed; canonical to the clean version. |
| Retired duplicate nobody needs to visit | Permanently redirect to the preferred version. |
| Different content sharing a template | Do not group pages just because their layout matches. |
| Equivalent content in another language | Review language annotations separately; see the hreflang guide below. |
Put the canonical link in the HTML head, using an absolute URL. Point internal links and the sitemap at the same preferred address. Do not use robots.txt or noindex as substitutes for canonicalization.
A tag is a request. Inspect the result.
In Search Console, inspect the duplicate and expand Page indexing. Compare the user-declared canonical with the Google-selected canonical. Use the indexed report: the live test cannot predict which URL Google will select.
Check the last crawl before judging an edit. Indexed information describes the version Google previously fetched, so a successful live test does not prove that the index has processed your new tag.
Copy this verification worksheet
Keep one record per duplicate pair. This separates the change you made from the outcome you observed.
Duplicate URL: Preferred URL: Why both addresses exist: Decision (keep / redirect / distinct content): Canonical currently served: Change deployed at: Google last crawled at: Google-selected canonical: Next check:
For example, record a campaign URL and its clean product URL as a pair. If Google last crawled before your edit, leave the outcome pending. Do not mark the worksheet complete solely because the tag now looks right.