Canonical Tag
An HTML tag that tells search engines which URL is the master version of duplicate or similar pages.
Key takeaways
- Canonical Tag is an HTML tag that tells search engines which URL is the master version of duplicate or similar pages.
- Add a self-referencing canonical to every indexable page, using the absolute URL on your primary domain.
- Avoid: canonicalising every page to the homepage, which tells Google to ignore the rest of the site.
What is Canonical Tag?
Canonical tags consolidate ranking signals to a single URL. Misuse causes pages to drop out of the index. Self referencing canonicals on every important page is a safe default.
Google sets out how it chooses between duplicate pages in its documentation on canonical URLs.
Why Canonical Tag matters for SEO in 2026
Duplicate and near-duplicate URLs split ranking signals and confuse search engines about which version to show. A correct canonical points them at one URL, so links, relevance and history consolidate instead of competing with each other.
For a wider view of where this fits, see our full SEO glossary or explore the SEO and GEO service we run for clients.
How to apply Canonical Tag on your site
Knowing the concept is only half of it. Work through these steps in order to put Canonical Tag into practice on your own pages:
- Add a self-referencing canonical to every indexable page, using the absolute URL on your primary domain.
- Point parameter, print and filtered versions at the clean URL they duplicate.
- Check Search Console's indexing report for pages where Google chose a different canonical than you declared.
Common mistakes to avoid
Most sites that struggle with Canonical Tag fall into the same traps. Check your pages against each of these before moving on:
- Canonicalising every page to the homepage, which tells Google to ignore the rest of the site.
- Pointing canonicals at URLs that redirect or return a 404.
- Mixing domains, such as canonicals on the apex domain while the site lives on www.
Questions about Canonical Tag
An HTML tag that tells search engines which URL is the master version of duplicate or similar pages.
Duplicate and near-duplicate URLs split ranking signals and confuse search engines about which version to show. A correct canonical points them at one URL, so links, relevance and history consolidate instead of competing with each other.
Start here: add a self-referencing canonical to every indexable page, using the absolute URL on your primary domain. Then point parameter, print and filtered versions at the clean URL they duplicate.
The most common is canonicalising every page to the homepage, which tells Google to ignore the rest of the site. Another is pointing canonicals at URLs that redirect or return a 404.