Definition
Canonical URL
The preferred URL search engines should treat as the main version of a page.
Definition
A canonical URL is declared with a canonical link tag in the page head to indicate the primary version of similar or duplicate content.
Meaning
It tells search engines which URL should receive credit when the same or similar content is available at multiple addresses.
Why It Matters
Canonical tags reduce duplicate-content confusion, consolidate ranking signals, and help keep reporting cleaner across URL variants.
History And Context
Major search engines introduced support for canonical tags in 2009 to help site owners manage duplicate URLs created by parameters, sorting, syndication, and CMS patterns.