Canonical URL
A tag that tells search engines which address is the ‘official’ one when the same page can be reached by several URLs.
Last revised 2026-09-07. Also available as markdown — request this URL with Accept: text/markdown.
In plain English
The same page can often be opened at slightly different addresses (with or without www, with tracking parameters, http vs https). To a search engine those can look like separate, duplicate pages — splitting your ranking strength between them.
A canonical tag is you pointing and saying “this one is the real address; credit it.” It consolidates all that strength onto a single URL.
How to fix / set it up
- Decide your preferred URL format (usually https + one of www/non-www).
- Add a self-referencing canonical link to every page's head.
- Point true duplicates (parameter URLs, print pages) at the main version.
The technical detail
Add <link rel="canonical" href="https://example.com/page"> in the page's <head>, pointing at the preferred absolute URL. Each page should canonicalise to itself unless it's a genuine duplicate.
Mismatched or missing canonicals cause duplicate-content dilution and unpredictable indexing.
FAQ
Does every page need a canonical?
It's good practice for every page to declare a self-referencing canonical, so duplicates via parameters or protocols don't split signals.
Is a canonical a redirect?
No — it's a hint, not a redirect. The duplicate URL still loads; search engines just credit the canonical one.