What is a Canonical URL?

In order to track users when launching marketing campaigns, some information is automatically added to each unique page URL. That URL is considered the same page with multiple versions and search engine crawlers find it hard to choose the right one. Search engines can index the canonical URL from several duplicate pages, that’s why it is very important to have a preferred/canonical URL added, in order to tell search engines which web page version you want to display to the visitors.