Glossary
Canonical URL
The address a site declares as the main version of a page, using the rel="canonical" link tag. Copies and parameter variants point to it, so search engines index one page instead of many.
Also called: rel=canonical.
Affiliate pages collect variants fast: tracking parameters, A/B copies, mobile versions. The canonical tag tells search engines which one counts, so the variants do not compete with each other in the index.
It matters mostly for publishers and for anyone building content sites for organic traffic; a paid-traffic pre-lander with noindex does not need one.
Related terms: Organic traffic, UTM parameters, Landing page.