Canonical URL

A mechanism that, when multiple URLs exist for the same content, specifies the URL that search engines should index preferentially.

Oct 31, 2026 / About 1 min read

SEO

A canonical URL is a mechanism that, when multiple URLs exist for the same content, declares to search engines: "Please index this URL as the official page." It is specified with the HTML <link rel="canonical"> tag.

Cases that require a canonical URL include when a page is accessible over both HTTP and HTTPS, when both with/without www versions exist, when large numbers of URLs with UTM parameters are generated, and when mobile and PC versions have different URLs. If these are left unaddressed, search engines may treat the same content as separate pages, which can lead to the "duplicate content problem" in which ranking signals are split.

The idea that "setting a canonical tag automatically redirects duplicate pages" is a misunderstanding. A canonical tag is an instruction aimed at search engines, and it does not move the user's browser to a different URL. To move users to the canonical URL, you use a redirect such as a 301 redirect.

As for the relationship between short URLs and canonical URLs, you set the URL of the final landing page as the canonical, not the short URL itself. A short URL is an intermediate URL that passes through a redirect. Google's official documentation on redirects (as of April 2026) explains that permanent redirects are used as a signal that the redirect target is the canonical URL, while temporary redirects are not used as that signal.

If you specify the wrong URL as the canonical, a page that should be indexed may stop appearing in search results. The "URL Inspection" tool in Google Search Console lets you check the canonical URL that Google recognizes.

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Related Terms

Short URL

A condensed version of a long URL that redirects to the original destination. Short URLs are easier to share and track.

301 Redirect

A permanent HTTP redirect that tells browsers and search engines the resource has moved permanently to a new URL.

UTM Parameter

Tags added to URLs that track the source, medium, and campaign name of traffic in analytics tools.

Permalink

A permanent URL that remains unchanged over time, providing a stable reference to a specific piece of content.

SEO-Friendly URL

A URL structure designed to be easily understood by both search engines and human users.

URL Canonicalization

A process that consolidates multiple URL variations pointing to the same content into a single canonical URL for search engines. It prevents duplicate indexing.

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FAQ

Where do you place the canonical tag?

Place it inside the HTML <head> section as <link rel="canonical" href="canonical URL">. Set only one per page; a self-referencing canonical that points to the page's own URL is also used.

When should you use a canonical tag and when a 301 redirect?

Use a canonical tag for duplicate pages that users need to be able to access, and a 301 redirect for old URLs that do not need to be accessed.

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