Instance: You've got an e-commerce Internet site with products internet pages for various measurements of a selected t-shirt.   You specify the first URL as the online search engine can have issue identifying which just one should be the main URL.  The following tutorial will demonstrate ways to help Canonical https://www.presta-addons-modules.com/en/seo/prestashop-seo-automatic-hreflang-tags-canonical-tags-on-all-pages.html