Skip to content
← SEO Dictionary

Canonical tag

A canonical tag is an HTML signal identifying the preferred URL for duplicate or very similar content. Google considers this signal alongside others when selecting a canonical page.

canonical tag · rel="canonical" · canonical seo

What does it look like in HTML?

<head>
  <link rel="canonical"
    href="https://example.com/product" />
</head>

Example in the HTML head. href contains the preferred absolute URL. The visitor is not redirected.

Which URL does a canonical identify?

Three similar product URLs identify /product as the preferred version using rel="canonical".
Similar versions identify a preferred URL. This is a signal, not a redirect; Google may choose a different URL.
Text version
  • /product
  • /product?color=black
  • /product?utm_source=example
  • rel="canonical" → /product

Why it matters

A product can be accessible through its main URL, filters and parameters. Identifying a preferred version helps consolidate content signals and reduce unnecessary crawling of duplicates.

How it works

A link element with rel="canonical" belongs in the HTML head. Its href points to the preferred absolute URL. Redirects, internal links, sitemaps and canonical annotations should support a consistent choice. A canonical URL is the preferred address; a canonical tag is one way to identify it.

Example

Example: /product and /product?color=blue show the same main content. Both versions can include: <link rel="canonical" href="https://example.com/product" /> This does not move the visitor to another address.

Common mistakes

Pointing a canonical tag to a 404 or redirecting URL complicates signals. A canonical tag does not replace a 301 when content has moved. Do not use noindex to force selection of another canonical. Google may select a different URL from the one proposed.

How can you check this in practice?

Inspect the canonical in the HTML head or HTTP Link header and open its destination. Align it with internal links and the sitemap. URL Inspection reports declared and Google-selected canonicals for the indexed version; a live test does not predict the final choice.

Distinctions and limitations

Canonical does not move visitors like a 301 or exclude a page like noindex. A self-referencing canonical identifies the preferred version but does not override other signals. Do not point to an unrelated product or language version merely to reduce URL counts.

When is canonical useful?

A product with tracking parameters may have identical main content. Identify its clean preferred version. When variants show different products or useful separate language versions, assess similarity before consolidating.

What needs to remain consistent?

The preferred URL should work and present corresponding content. Internal links, sitemap and canonical should not point at three different versions. Avoid canonical chains, loops and failing URLs.

Official sources

Editorial responsibility: Martin Zhelyazkov · Founder of Z-Consult

Updated: 05/11/2026

For a correction or question: office@z-consult.bg