What is Canonical Tag and How it's works ?

Nowadays most of the content management and Ecommerce websites has the problem with different URL’s with same content, to overcome this kind of issues on different search engines we need to implement Canonical Tag on the header part the pages. Here is the example of Duplicate Content Pages URL’s

http://www.example.com/page1 ( Origional One )

http://www.example.com/page1?source=organic ( Duplicate )

http://www.example.com/page1?campaignid=3532 ( Duplicate )

If you are not implemented this tag on your pages, search engines will consider both pages are same content so, it will treat as Duplicate Pages and the Title, Description and Keywords will be consider as Duplicate. To solve this types issues  need to add Canonical HTML Tag on web pages. Here is the Tag,

<link rel="canonical" href="http://www.example.com/page1" />

By insert this Tag on second and third pages, we are telling that these page are original content of “ http://www.example.com/page1 ”

This is one of the method to solve Duplicate Page Content Issue. Here all the pages will index in search engines but it will consider only one URL as Original.