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How Canonical Tags Can Save You from Duplicate Content Issues

Let’s start off with a hypothetical situation. You are the owner of an online clothing boutique. Your classic t-shirt is a big seller, and it comes in a variety of colors. Every time a customer selects a different color of the t-shirt to view, the URL changes slightly to show them the selected color. All of these pages are necessary and useful to the customer but in the eyes of a crawler these slightly different URL’s look like duplicate content.

You start to notice that your t-shirt page has slipped from the rankings, and you are getting less traffic to your site. What do you do?

Canonical Tags to the Rescue!

Canonical tags were first used by search engine crawlers back in 2009. Before canonical tags, there was no way to let a crawler know that this seemingly duplicate content they were picking up was actually useful and necessary for your customer experience. Now, with the help of a canonical tag you can identify an “authoritative” page, and let crawlers know that while there are variants of this original page, that it is the original page that should be indexed and shown in the search results.

What Exactly Is a Canonical Tag?

Plainly put, a canonical tag is a line of HTML code that is placed in the <head> of a page to indicate that it is a variant of the original, authoritative page.

  <link rel=”canonical” href=”original page here” />

Why Do We Need Canonical Tags?

There are numerous issues that can arise when a crawler is seeing the same, or very similar content on different URLS.

canonical meme

Some of these issues include:

  • The search engine doesn’t know which version(s) to include or exclude from their indices.
  • Search engines don’t know whether to direct link metrics (trust, authority, link juice, etc.) to one page, or to keep it separated between the multiple versions.
  • Search engines don’t know which version(s) of the page to rank for query results.

301 VS. Canonical Tags

You may be wondering if a 301 redirect is what you need in this situation; however, there are some core differences between the two, as listed below.

 

301Canonical
  • Redirects bots, humans & link juice
  • Is a signal to Google that the 301’d page no longer exists
  • Possible within and across domains
  • Acts as a directive
  • Redirects bots & link juice only
  • Is a signal to Google that there is one authoritative page, but both should exist
  • Only possible within a domain
  • Is only a hint

While you can see that canonical tags act only as a suggestion to search engine crawlers, they are currently our best way to let crawlers know that while there is an authoritative page, the variants of this page need to also exist.

When to Use a Canonical Tag

You will want to implement canonical tags whenever multiple URLs are being generated by your site for virtually the same content, and all of those pages need to be accessible to humans. If a page no longer exists or does not need to be accessible by humans, a 301 will do the trick.

Let’s go back to our online boutique. You decide to install canonical tags on all your product pages to ensure that search engine crawlers understand that there is a reason why you have what is seemingly duplicate content. Your rankings return, and business is better than ever!

Let us know about your knowledge or experience with canonical tags in the comments below.