Do you know you have lots of Duplicate content on your site/blog?
If you don’t know, This article is for you. In 2009, All major search engines like google, yahoo and bing started supporting Canonical tag. If you don’t know about it, No worries, In next few minutes you will get the whole logic behind it.
To understand Canonical tag, You must know about Duplicate content. It is the content which is served same on many URLs. Having lots of Duplicate content on your site is very bad for site’s health and search engines may Penalize them. First, Let us know about Duplicate content and how it is generated on any site unknowingly.
1. How Duplicate content is Created
Nowadays, Majority of blogs are powered by WordPress and they all contains duplicate content. It is because every WordPress site has Dynamic URLs and they all Serve the same content to User.
For example, Every comment on WordPress site has unique URL. It’s URL of comment, but it shows Whole article as well as every comment on the page to the user as well as search engines. To make it easy to understand, Let us take a Live example.
URL of any article on WordPress:
URL of any comment on WordPress:
Both the URLs are different. We can understand that Second one is just to identify comment. While Both the URL serves the same page which is Article page. But search engine can’t understand that.
For the search engine, They are two URLs serving same content which is the whole article, comments and whole page. Yes, It is dynamic URL and Let me tell you that any search engine can crawl dynamic URL too! Even search engine can index Dynamic URLs.
Now you can understand How Duplicate content is created. For users, It’s not but search engines considers it a Duplicate content even if it is in a same website. For example, There is one article in which there are 50 comments. For search engine, there are at least 51 URLs serving the same content. Here, the Search engine can’t decide the URL which is to be indexed.
That is how duplicate content is generated unknowingly on your websites. To solve this problem, All major search engines started supporting Canonical tag.
2. What is canonical tag?
To make It easy to understand, Let’s keep taking an example of an article containing 50 comments. As we know that Search engines are confused about the URL that is to be indexed.
Now, We have to tell search engine a URL to be indexed. After telling the search engine a URL that is to be indexed, It will index that URL only. As we know that the main URL of that article is http://www.domain.com/article-URL/, We can tell search engine to index that URL out of 51 URLs the search engine got.
Now, Whenever search engine will crawl that 50 comments and 1 Main URL of article, It will only index The main URL only. It is because, We told the search engine to index main URL only using Canonical tag.
Practically, It is not like that. It is just to explain you the work of canonical tag. Now, As you know the function of Canonical tag, Let me explain you practically.
What happens whenever we give 301 Redirect? Simple, Every user will be permanently redirected from 1 URL to another. It will redirect even search engine to another URL.
In case of Canonical tag, It will only redirect Search engine to the another URL. The URL that is to be indexed. In the href=”Link_here” section of the Canonical tag, we have to put the URL of the page we want to index. If we will put the URL of main article in the 50 comment URLs, Search engine will be redirected to the main article page while users will not be redirected.
Now, We have 51 Different URLs serving the same content but for search engine it is only 1 URL because other 50 URLs are redirecting search engine to the URL that we want to index.
That is how Canonical tag works. Now, Google or any search engines will get 51 Different URLs containing the same content but they will be redirected to 1 main URL. Now, the search engine will index that main URL only.
3. How to use Canonical tag
It is very simple to Use Canonical tag. Here is the syntax of Canonical tag.
<link rel=”canonical” href=”ORIGINAL_LINK”>
You just have to place this Tag in the <head> section of the page from which you want to redirect search engine. Maybe Comment Page or any dynamic URL. Now you will think, How I will put this tag in 50 comment pages. Let me give you one good news, If you are using wordpress then you don’t have to worry about Canonicalization. It is because, Whenever you will install Yoast SEO plugin, it will automatically canonicalize each and every dynamic URL to main one.
If you are copying data from other sites, you can put the link of the page containing original content in href section of the canonical tag.
Back again to our old but gold example, we have to put,
<link rel=”canonical” href=”http://www.domain.com/article-url”>
This canonical tag in every comment URL to redirect search engine to the URL containing original content.
By this way, you can use canonical tag to help search engine to find original content which can be indexed.
4. Importance of Canonical tag in SEO
It is very important to use canonical tag. We can say that if you will not use canonical tag, your site may get penalize or search engine may index wrong URLs too!
To stop these all things, you have to use canonical tag to help search engine to find original content which can be indexed without any mistake.
If you are using wordpress, you don’t have to worry about canonicalization because whenever you will install Yoast SEO plugin which is the best SEO plugin for wordpress, It will automatically canonicalize each and every URL of your page to the main URLs that is to be indexed by the search engines.