Many websites these days have multiple web pages or URLs with the same content to make the content look good on various devices and operating systems. However, search engines often consider the URLs as duplicate versions of the same web page while indexing the website. The canonical tags help website developers and webmasters to differentiate between the master page and duplicate pages. Webmasters should keep a tab on how to add Canonical tags, the best practices, and common mistakes to avoid for best results in SEO.