From an SEO point of view here is the definition of a canonical URL: Canonical URL: the search engine friendly URL that you want the search engines to treat as authoritative. In other words, a canonical URL is the URL that you want visitors to see. Quite often canonical URLs were used to describe the homepage

A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical" or "preferred" version of a web page as part of search engine optimization. It is described in RFC 6596, which went live in April 2012.

The web index inviting URL that you need the web crawlers to regard as definitive. At the end of the day, a standard URL is the URL that you need guests to see.