This attribute comes in clutch for pages that serve as the default version for end users whose language or locale doesn’t match any hreflang tags.  Canonical URLs are employed to avoid replicate written content and indicate to search engines like google which site would be the "primary" web page. This https://www.presta-addons-modules.com/en/opencart-seo-automatic-google-rich-snippets-json-ld-integration-opengraph-twitter-tags-schemaorg.html