Duplicate content or almost similar content can cause confusion for the search engine to display the right page. This is not the right sign in aspect to Search Engine Optimization. Hence canonicalization allows the search engine to focus on a particular page irrespective of URLs. The canonical tag is one of the ways of canonicalization. To know more about Canonical URL Click here
Meaning of Canonical URL
rel=canonical tag is an HTML tag that allows Google and other search engines to prevent the duplicate content problem. It any website have duplicate or almost similar content at different URLs then webmaster can face the duplicate issue. This can cause a serious negative impact in the ranking.
When the webmaster has several URL for the same product, canonicalization is the process of giving authority to one of them. Canonical URL informs Google and other search engines to index and to rank particular URL out of several URLs of similar content. Take example:

The user can type the address in various ways as
- xyz.com
- http://www.xyz.com
- http:// http://www.xyz.com
- https://www.xyz.com
Each URL mentioned above is referring to the same content of a particular website but the search engine will treat them as different. To deal with this, rel=canonical is strongly recommended.
Steps to apply Canonical URL
Before picking canonical URL out of several URL, some parameter related to content at different URL needs to match otherwise content at different URLs are considered as different.
Things need to match:
- Contents like text, images or videos need to match.
- The headline
- Inbound and outbound links in content
Things don’t need to match:
- URLs don’t need to match
- The title of topics
- Navigation
- Site branding i.e. format in which that page looks.
After observing these parameter, steps need to follow:
- Select any one of the above URL as the canonical URL. Let’s say I have selected http://www.xyz.com. Selection is done on the basis of:
- If the content is not exactly similar then select that URL which you think is most important.
- If the content is exactly similar then select on the basis of most inbound and outbound links used or most user or subscriber.
- Add a rel=canonical tag to the selected URL. The format to apply is <link rel=”canonical” href=”http://www.xyz.com”
So if the user searches with different URLs, Google and other search engines will redirect to the canonical version of URL. This improves ranking.
With the help of canonical tag, you can also purchase or rent any content from other domain and can redirect to your domain. And if you are running different websites you can choose one of them to get SEO advantages with the help of Canonical tag.