Illustration: You've got an e-commerce Web site with solution pages for various measurements of a selected t-shirt.   You specify the first URL since the online search engine might have problems deciding which a single should be the key URL.  The next tutorial will demonstrate how to permit Canonical URLs https://www.presta-addons-modules.com/en/seo/prestashop-seo-automatic-hreflang-tags-canonical-tags-on-all-pages.html