Quick answer: A canonical URL is a hint about the preferred version of a page. It can reduce duplicate-URL confusion, but it is not a redirect and it does not force a visitor to go anywhere.
Where the canonical appears
Most canonical declarations are placed in the HTML head as a link element with rel="canonical" and an absolute preferred URL. HTTP headers can also be used for some non-HTML resources.
Canonical is not the same as redirect
A redirect changes where the browser goes. A canonical tag leaves the visitor on the current page and communicates a preference to search engines. That means a URL can return 200 while declaring a different canonical.
Common mismatch patterns
Tracking variants often canonicalize to a clean URL. Paginated or filtered pages may use more complex strategies. A migration problem can also produce an accidental canonical back to an obsolete domain or an unrelated page.
What to check
Compare the URL you requested, the final URL after redirects and the canonical declaration. If all three differ, review whether that is intentional. Also ensure the preferred URL itself is reachable and not stuck in another redirect chain.
Use the tag as a diagnostic signal
URLClinic surfaces canonical information as part of a wider URL diagnosis. It does not score a different canonical as automatically wrong because many valid site architectures intentionally use it.
Use the tools
For a live URL, URL Checkup combines redirect tracing, metadata, tracking detection and health scoring. If the link is already broken, Smart URL Recovery can search the same site for likely replacement pages. For long-lived public links or printed QR codes, Rescue Link adds a stable managed destination.
Important limitation
URLClinic provides technical information and workflow tools. It does not certify the identity, safety, legality or accuracy of third-party websites. Verify important destinations independently.