Glossary · SEO & AI search
What is canonical URL?
A canonical URL is the preferred version of a web page that search engines should index and rank when the same or very similar content is available at several URLs, usually declared with a rel="canonical" link element.
Also called: rel=canonical, Canonical tag
Updated
How do canonical URLs work?
<link rel="canonical" href="https://example.com/pricing" />
The tag goes in the page's <head> (or as an HTTP Link header for PDFs and other files). Google treats it as a strong hint, not a command: it also weighs redirects, internal links, sitemaps and HTTPS when choosing the canonical, and Search Console's URL Inspection shows both the user-declared and the Google-selected canonical.
Canonical URL examples
| Duplicate URL | Canonical |
|---|---|
/pricing?utm_source=newsletter | /pricing |
/blog/post/ and /blog/post | Pick one and redirect the other |
http:// and https:// | https:// (with a redirect) |
/shoes?sort=price | /shoes |
| Syndicated copy of your article on another site | Your original URL (if the partner agrees to add it) |
Why canonical URLs matter
Without a clear canonical, ranking signals split between duplicates, the wrong URL may rank (a tagged campaign URL, say), and crawlers waste time on copies. Every page should have a self-referencing canonical to its clean URL, so UTM-tagged links never compete with the page itself.
Common canonical mistakes
- Canonicalizing every paginated page to page 1, which hides the rest from indexing.
- Canonical pointing to a URL that redirects, 404s or is noindexed.
- Relative or http canonicals on an https site.
- Several conflicting canonical tags on one page (often from a plugin plus a template).
- Canonicals that disagree with sitemaps and internal links.
Canonical URLs and analytics
Analytics and canonicals solve the same duplication problem from two sides. VisitTrack reports pages by path, so ?utm_source= variants don't split one page into several rows, while the UTM values are still captured as campaign data. Every page in this glossary declares a canonical through its metadata. Check how a URL's title and description will appear with the SERP snippet preview.
Frequently asked questions
Should every page have a canonical tag?
It's good practice. A self-referencing canonical on every page tells search engines which URL is preferred and protects against duplicates created by tracking parameters or alternate paths.
Is a canonical tag the same as a 301 redirect?
No. A 301 redirect sends users and crawlers to another URL; a canonical tag leaves the page accessible but asks search engines to index the preferred URL. Use a redirect when the duplicate shouldn't exist for users either.
Related terms
- Crawl budgetCrawl budget is the number of URLs on a site that a search engine crawler can and wants to crawl in a given period — determined, in Google's terms, by crawl capacity (how much your server can handle) and crawl demand (how much Google wants to recrawl your content).
- Structured dataStructured data is machine-readable markup added to a web page — usually Schema.org vocabulary written as JSON-LD — that describes what the page contains (an article, product, organization, FAQ, defined term) so search engines and other systems can understand it precisely.
- UTM parametersUTM parameters are five standard query-string tags — utm_source, utm_medium, utm_campaign, utm_term and utm_content — added to a link so analytics tools can attribute the visit to a specific source, channel and campaign.
- Google Search ConsoleGoogle Search Console is Google's free service that shows how a website performs in Google Search — the queries it appears for, its clicks, impressions, click-through rate and average position — and reports on crawling, indexing and technical issues.
- robots.txtrobots.txt is a plain-text file at the root of a website (/robots.txt) that tells crawlers which URLs they are allowed or not allowed to request, using the Robots Exclusion Protocol, standardized as RFC 9309 in 2022.
Tools and guides
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