The Canonical Tag, or canonical url tag, is 2009 addition to coding that allows webmasters and site owners to get rid of indexed duplicate content that has been self-created. It 2016, it remains just as relevant. It functions by redirecting search engines to the original version of the content. When your search engine tries to find information, it will search the web. Canonicalization allows the search engine to identify the original source of content, which eliminates duplicate content in their indexes, ensuring that they redirect people to originals rather than copies.

This is a great tool for people who are showing information multiple times within their own webpage. By using a canonical url tag, you can instruct the search engine to use the original and first version of your content, rather than the duplicates spread about your page. This way, if someone wants to go to the original source, they will go to the page you want, rather than other areas you have that content. Ultimately, the canonical url tag is a way to help search engines and site owners to organize their pages and content effectively.

How the Canonical Tag Applies to SEO

You’re probably wondering how all of this applies to you. Essentially, it boils down to SEO. Although there are other ways to use the canonical tag to your benefit, it is mostly about maximizing for SEO. Canonicalization is when individual pages are found and searched from multiple URLs. The issue with this process is that the same content is being attributed to – and distributed across – multiple different URLs. This splits up your content for the search engine, and makes it think that content pulled is from a variety of sources and not yours.

This spreads you out and doesn’t properly attribute results to your pages. You want all of your traffic and searches to be recorded together, ensuring your page remains popular and ranks. The canonical url tag serves as a way of telling search engines where your content comes from, ensuring that you are credited for your original content and that it all helps rank as one unit. This is a huge advancement for SEO purposes, and a great means of protecting your rankings from people who just want to steal your content ranks.

Canonicalization Errors

Please note that these apply to the two most common web servers, Apache and Microsoft Internet Information Services.

If your homepage is split between urls, like this:;;;, then your inbound links will be split between the pages, decreasing the search engines volume for each page. Search engines value each as it’s own thing, and account for them in this manner. What does this mean for you? Your inbound links are split and their value diminished.

The good news is that there are solutions that exists, namely in the form of redirection. By coding redirections, URLs can be combined or changed to ensure you reach the proper page. The two major types of redirects are a 301, which indicates an HTTP status code of “Moved Permanently”, and a 302, which indicates a temporary redirect.

Although these essentially serve the same function for the user, search engines read these two redirects very differently. A 301 transfers much of the value over to the new page, retaining approximately 90 to 99 percent of its value. On the other hand, 302s transfer no value. This is because the automatic redirect the server performs for a 301 knows to direct this to the main site, whereas a 302 knows it is temporary, and places less value on the actual link itself.

When users search, the server knows they mean to go to, because this is the correct way of displaying the page domain. However, people rarely – if ever – type that out. The server redirects you automatically and gets you to where you want to be. The downside, as the site owner, is that this redirect splits your pages, and makes it two pages for the search engine to see. Therefore, traffic to one page, and the redirect, will take away some of your value from the other page. The best way to ensure you retain this and avoid redirects is by ensuring that your internal links all read properly, including the backslash.

Other Solutions

Don’t generate duplicate content in the first place

It may seem like an obvious solution – maybe even too obvious; but try to avoid producing duplicate content. If you can avoid creating the same content then this won’t be an issue but sometimes unavoidable. Obviously, duplicate content is an issue for you, so there are a couple other options to try besides canonical tags and.

301 redirect

They entire purpose of using a 301 redirect on your webserver is to let the search engine know which url is the canonical one. Therefore, in effect, the best way to direct people to your canonical website is through a 301 redirect.

In the case of a 301 redirect, the search engine is actually redirecting the person trying to find your website to the canonical site, ensuring they get to the right page. This makes both you and the user happy. While the use of a canonical tag essentially serves the same function and gives them the appropriate content, it does not function the same for the search engine. In this case, it does not actually redirect them back to the canonical link, but gives them the appropriate content. The best way to consolidate two pages and get rid of the problem with duplicate content is to use a 301 redirect.

Although they function differently, and the user is not actually sent to the canonical page, canonical tags seem to register the same with search engines as a 301 redirect in terms of authority and PageRank. Just as the 301 does, there is some loss, but much of the value is transferred.

Meta noindex tag

Setting your page to “noindex, follow” is another way of solving this problem. Although it doesn’t work as effective as a 301 redirect or a canonical tag, it still serves a similar function in terms of search engine indexation. By making your page “noindex, follow”, search engine bots will know to crawl your page but not index it, ensuring that it does not interfere with your canonical page in their indexes. If you want your pages to be indexed, then this is going to be an issue for you and a canonical is a better method.

A good example of a place to use this is on a blog. Since you have archived posts that are sorted by various different categories, a 301 redirect or canonical link won’t work. By using the noindex, follow option you will keep these new and relevant according to the search engine and ensure your content is easily found by your users.

Google Webmaster Tools

Although this is by no means the same solution and will not reap the same results, setting your Webmaster Tools properly can help your SEO. Although this only works with Google, setting your domain site and URL parameters will let you tell Google information about your page that will help them search and index you. This is not a real alternative to the canonical tag, but it should be used for Google regardless if this is an issue you are facing.

How Does This All Affect the Canonical Tag?

Using the canonical tag in your code will essentially perform the same function of a 301 redirect. The benefit of doing it this way is that it’s much simpler and takes less time. Including this in your code will then ensure your page retains the same value to search engines and that they know where the original source is. This will help make sure you remain the top searched page for your content and niche market. However, you will want to ensure that you only use this if you are not able to do a 301 redirect for some reason, as this is a better solution.

For more information on canonical tags, check out SEO advice: url canonicalization, Moz’s article on Canonicalization, or Google’s Search Console Help information.

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