Rel=Canonical Tag - Importance In SEO & Content Marketing

Five years ago, Google introduced rel=canonical tag, a single line HTML code but really very powerful. Most of the webmasters are confused and still not aware of the use of rel=canonical tag & its advantages properly.

I was reading some article and I found out a few very interesting things about rel=canonical tag, so here I am sharing how to use and take the best out from this tag.

credit:orangesoda.com

What is Rel=Canonical tag

Rel=Canonical is a HTML tag used on a webpage to Indicate Google about the original & master copy of a webpage.

It is basically used to tell Google about the preferred url of a page to consider, when there are multiple duplicate versions present for the same page.

Google is very strict on duplicate content issue, So when there are multiple versions of a url for a page created by itself or by users then there are possibilities that Google may index the other duplicate urls and rank it higher as compared to the original page.

OR

Take your page rankings down over duplicate content issue. You may become the victim of panda penalties due to this duplicate content.

Many webmasters have this confusion that rel=canonical & 301 re-directions are the same and you can use anyone of them, but it's not like that.

When you can use Rel=Canonical?

• On duplicate urls with tracking codes
• On duplicate urls with session ids
• Landing pages on your website
• In-case you are not sufficient enough to implement a server side or a 301 redirection
• Syndicating your content while content marketing activity (Cross-domain)
• You can use rel=canonical tag on pages with duplicate content or near duplicate content

Note: Here near duplicate means pages like eCommerce website where for a specific product everything is same but only color is different for different variants.

Read: 13 Link Building Most of the webmasters are doing

What is the difference between Rel=Canonical & 301 redirection

This is really very important thing to know. Rel=canonical tag & 301 redirection are similar from the SEO point of view but both of these techniques are not interchangeable.

Rel=canonical is a page level tag and needs to be implemented on each page while 301 redirect is implemented on URL level.

Example:

# Task - Redirect Visitors from PageA------->PageB or use canonical tag 

Difference 1:

If you apply a 301 redirection on PageA to PageB then it redirects all the visitors coming to PageA to PageB. In this case visitors will not be able to see the PageA after redirection.

While in rel=canonical, It does not redirects the visitor from PageA to PageB. It just tells Google that the original version is actually PageB, so Google should cache & index PageB and show it in search results rather than PageA.

Difference 2:

In 301 re-direction you cannot see the page even if you have the exact old url of the page. When crawler comes to the old page it is redirected to the new page.

In rel=canonical tag, you can see the old page using its exact url. When crawler comes to the old page, It is notified about the preferred version and redirected to it.

A few points to remember about rel=canonical tag & 301 redirection.

Read: 15+ natural link building techniques works for every website

Which one should I Use? Rel=canonical or 301 Redirection

If you want to consolidate new and old version of pages permanently and remove duplicates then you should use 301 re-directions.
But

If you want to keep both the copies of a pages live for your users and want to show only 1 version in search results then you should use rel=canonical.

If you are going for a permanent redirection from old website to new website then you should go for 301 redirection or a server side redirection, But if all these options are not possible then you should go for the rel=canonical tag option. (Make sure both the copies of webpages are same or nearly same.)

301 redirection gives a clear signal to the crawler and users that which url should be indexed and it is widely supported by all the search engines.

While rel=canonical tag is just a hint for search engines.

Does rel=canonical Pass Authority & SEO Page rank?

Just like a 301 redirection, rel=canonical also passes authority and page rank if used properly.

Will Google cache or index those duplicate pages? NO

If you apply rel=canonical tag on a page then Google neither cache nor index any copy of the duplicate pages, they also do not appear in search results. Only the original version of webpage is cached, indexed and ranked in search results.

Here take a look at a practical test done by @tonyadam on his own website.

How to Use Rel=Canonical to Handle Duplicate Content on the same Domain

Let me explain this with an example:

There are a few urls for a single page

PageA - www.example.com/accessories/nivia-comb

PageB - www.example.com/accessories/nivia-comb/colorid=2

PageC - www.example.com/accessories/nivia-comb/colorid=3

PageD - www.example.com/accessories/nivia-comb/sessionid=19090

Here comes the issue of duplicate content. 

To resolve this issue and to tell Google that PageA is the original version and Page B, C & D are the duplicate urls of PageA, use Rel=Canonical tag on these pages.

Place <link rel="canonical" href="www.example.com/accessories/nivia-comb" /> in the <head></head> section of the page source code.

It will indicate Google that the original page is the PageA and others are just the duplicate ones. So that original preferred copy of PageA will be cached and indexed by search engine and it will rank in search results.

All the SEO values will also be passed to the PageA url i.e. Google will not cache or index PageB, C & D urls, and they will not appear in search results 

and if any link is pointing out to the Page B, C or D url then the value of that link will be passed to the PageA url.

JCPenney example:

Here are the two urls of a product page at JCPenney store

Url1 - http://www.jcpenney.com/gifts/for-him/the-foundry-supply-co-performance-pocket-tee-big-tall/prod.jump?ppId=pp5002260206&catId=cat1002310004&subcatId=cat100250139&deptId=dept20000014&&colorizedImg=DP0318201419090047C.tif 

Url2 - http://www.jcpenney.com/gifts/for-him/the-foundry-supply-co-performance-pocket-tee-big-tall/prod.jump?ppId=pp5002260206

If you check both the urls in browser, then you will see that both urls are pointing out one single page, the only thing that is different here is the path used by user to reach to that page.

Issues:

In the url1, multiple tracking ids are being added to the url making it very long. This url will be cached & indexed by Search engine. Now if any user link to that url or it get shared in social media then its value will increase in terms of SEO and it will start ranking higher as compared to url 2. 

Duplicate content issue will also come in picture because of this.

Solution to the Issue:

include rel=canonical tag in the page source code, so that whenever there is a duplicate version will created, It will be handled by this tag.

If you see the page source code of url1, canonical tag for the preferred page is already present there.

<link rel="canonical" href="http://www.jcpenney.com/gifts/for-him/the-foundry-supply-co-performance-pocket-tee-big-tall/prod.jump?ppId=pp5002260206"></link>

This canonical tag pointing out to the original copy of the page is telling Google that this (the above link in the image) is the original version and others are just the duplicate ones. So cache, index and rank this version of url.

Note: Here one thing to keep in mind that "there is only one page with multiple generated urls. So when it comes to place a canonical tag, It is always placed in the <head></head> of the original page source code.

How to Use Rel=Canonical Cross-domain for Content Syndication

There are many authors who write high quality content on their blog and publish it among various other high authority website for content marketing. Is this the correct strategy to follow? Don't they face the duplicate content issue?

Well, there is a content syndication technique which a very few marketers know about. It is called Cross-domain rel=canonical tagging. This technique is totally different than the dead guest blogging.

In cross domain rel=canonical, you are increasing eye balls on your content by publishing it on different high authority blogs without any duplicate content issue. All the SEO value is also passed to your original content only.

Advantages 

• More number of readers for your content, Build your author rank and followers through content marketing
• The original source of content is preferred by Google for indexing and ranking in search results
• Get value of all the links pointing out to your syndicated content on different websites
• Increases content popularity among readers, which results in more number of social shares and back links

How to Implement Cross Domain rel=canonical tag

Lets understand this through an example.

Neil patel from Quicksprout has published an article 

Url - http://www.quicksprout.com/2014/04/18/what-is-a-good-link-profile-and-how-do-you-get-one/

Neil has published exactly the same article on Search Engine Journal

Url - http://www.searchenginejournal.com/good-link-profile-get-one/104409/

If you look for this article in search results using query - "What Is a “Good Link Profile” and How Do You Get One? searchenginejournal" 

This search engine journal's page is not present in search results.

WHY? Lets find out.

Now to check the last caching date of above search engine journal url, Enter query - cache:http://www.searchenginejournal.com/good-link-profile-get-one/104409/

Google is actually caching the original source of that article at quicksprout.com.

Now go to the page source of that search engine journal's article page and check for rel="canonical" using Ctrl+F,

You can see the canonical tag at search engine journal's page code in above image, the link is pointing out to original article at quicksprout.com.

Key takeaways from above examples:

The duplicate version of article at search engine journal website is neither getting cached or indexed nor it is appearing in search results.

The rel=canonical tag present at the page is pointing out to the quicksprout url, telling Google that this is the original source to index and rank in search results.

Google will pass a the value of all the links pointing out to above Search engine journal's article to the quicksprout article.

Check out this useful whiteboard friday by Rank fishkin from MOZ about the use of cross-domain rel=canonical tag for content syndication.

Key Points to Remember

## You can tag only the exact same pages or similar pages. A slight difference in acceptable but tagging completely different pages is not recommended.

## Rel=Canonical is a page level tagging and should be implemented on each page of a website. Implementing only at homepage for the whole website doesn't work here.

## Always ask your content publishers to user rel=canonical tag on their website, If they are using content published originally by you.

## To handle paginated content on a website, It is recommended to use a rel=canonical tag to a "view all" page OR use rel=prev/next.

## Using rel=canonical tag on the original content page is also fine. Google understand self referencing canonical tags and there is no harm in using that.

## Don't use multiple rel=canonical tags on a page otherwise Google will ignore all the tags.

## For moving from old site to new site, Always prefer 301 redirection, because canonical tag is just a hint for Google and other search engines treats it differently.

## Do not use noindex robots meta tags or block the page with robots.txt where rel=canonical is implemented otherwise search engine will not be able to crawl or read your canonical tag on that page.

## You can reach out to this article by Dr. Peter about questions related to rel=canonical.

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