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Glossary · Technical SEO

canonical tag

Also called rel="canonical", canonical URL, canonical link

Reviewed 30 Oct 2026 By Madiha Fatima 3 min read Check it yourself: yes, free

3 min
Definition

A canonical tag is a line of code in a page’s header that tells search engines which version of a page is the original when the same content can be reached at more than one web address. Google then credits that one address with the rankings instead of splitting them across the copies.

It is a request, not an order. Google usually respects it, but it will ignore a canonical that points somewhere unrelated.

Short version: one page, one address, one set of rankings.
Why it matters for your business

One page, five addresses,
a fifth of the credit each.

Almost every small business site serves the same page at several addresses without anyone deciding to. The www and non-www versions, http and https, a tracking code added by a newsletter link, a trailing slash, a Shopify product that lives under three different collections. To you it is one page. To Google it is five pages with identical content, and the links and signals that should build one strong page get shared out across five weak ones.

A canonical tag collapses them back into one. The usual symptom of a missing or wrong one is a page that should rank and does not, or a page you did not want in search showing up instead of the one you did. Fixing it costs nothing and is one of the first things a site audit should check.

The reverse mistake is worse. A site that points every page’s canonical at the homepage, usually by a theme setting nobody understood, is asking Google to ignore every page except one. We see it on roughly one in ten sites that come to us.

Example

A Shopify store with one candle
in three collections.

What the store owner sees

One product, “Fig and cedar candle”, added to the Bestsellers, Gifts and Autumn collections. Three ways in, one product page.

/collections/bestsellers/products/fig-cedar /collections/gifts/products/fig-cedar /collections/autumn/products/fig-cedar /products/fig-cedar
What Google sees

Four addresses with the same title, photos and description. Shopify adds a canonical tag to all four pointing at the plain /products/fig-cedar address, so Google ranks that one and treats the others as routes to it. Delete that tag in a theme edit, which happens more than it should, and the product starts competing with itself.

Try it
  • /products/fig-cedar
  • /collections/bestsellers/products/fig-cedar
  • /collections/gifts/products/fig-cedar
  • /collections/autumn/products/fig-cedar

One page ranks. The other three hand their credit to it.

How to check it on your site

Four checks, no tools to pay for.

Tick each one as you go. 0 of 4 checked on your site.

  1. Look at the page source

    Open any page, press Ctrl+U (or Cmd+Option+U on a Mac) and search for canonical. You should find one line: <link rel="canonical" href="...">. The address inside it should be the clean version of the page you are on.

  2. Ask Google which address it chose

    In Google Search Console, paste the page into URL inspection. The report shows “User-declared canonical” next to “Google-selected canonical”. When they differ, Google disagreed with your tag, and the page it picked is the one that ranks.

  3. Test the obvious duplicates

    Type your homepage with www and without, with http and https, with and without the trailing slash. Each should either redirect to one version with a 301 redirect or carry a canonical pointing to it. Both is fine. Neither is the problem.

  4. Make sure they do not all point home

    Check three inner pages. If every canonical reads your homepage address, a theme or plugin setting is wrong and most of your site is asking not to be ranked. That is a same-day fix for whoever built the site, and it should be free.

Related terms

Usually in the same sentence.

Read next

Where this shows up in practice.

Pricing & transparency Agency vs freelancer vs DIY website

What each option actually includes, canonicals and redirects among them, with real prices for all three.

 Pricing & transparency The fees agencies hide

“Technical fixes” billed by the hour is one of them. Here is how to spot it in a proposal.

 Service SEO & AI search

Technical SEO, including the canonical and redirect audit, is month one of the rolling SEO work.
Related service

Canonical and redirect checks are part of the technical audit in month one of the SEO service, and part of every site we build. Prices are on the price list, not on a call.

See the SEO service
Reviewed by Madiha Fatima, founder of 99creatix

Every entry in this glossary is written and checked by the person who runs the agency, reviewed at least once a quarter and dated. Last reviewed 30 October 2026.

Spotted an error or a term we are missing? Tell us and it is fixed within the week.

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