What is the use of canonical link?

[smmexpertss]

In February 2009, six years to the day from when this is published, Google, Bing and Yahoo! introduced the rel=canonical link element (Matt’s post is probably the easiest reading). While the idea is simple, the specifics of how to use it turn out to be complex. The basic premise is: if you have several similar versions of the same content, you pick one “canonical” version and point the search engines at that. This solves a duplicate content problem where search engines don’t know which version of the content to show. This article takes you through the use cases and the anti use cases