A canonical URL quite sometimes used to describe the homepage of the sites. Mostly the URL which we want visitors to see.
The canonical URL make search engine identifies certain similar URLs that are actually same. Sometimes in a website the content is accessible via multiple URLs. If the webpage using rel=canonical it helps in ranking of the original page.
The webmasters get assisted to identify the duplicate content issues using the canonical URLs. It does this by specifying the “canonical” or “preferred”. It improves SEO of the site also.
Read more about What are Canonical Url’s ? visit Findnerd.