What Are Canonical Tags and When Should You Use Them?

Canonical tags come in many guises – rel canonical, canonical URL tag, even rel=canonical – but despite their different names, they all mean the same thing.

The canonical tag tells a search engine which page serves as the ‘master’ copy. Using a meta tag in your site’s HTML header, you can reduce duplicate returns of the same content with different URL extensions in searches. How? Because canonical tags tell a search engine which version of your content came first, and which you want to show.

With fewer duplicates in any given search, your canonical page gets boosted higher in the search results, sending more hits to your original content. But canonical tags are complex – and in this article, we’ll explain everything you need to know about them from best practice uses to how and when you should use a canonical tag, and if there are alternative solutions that would work better for you given your situation. Let’s get started.

Set a canonical tag for your homepage

Starting somewhere relatively simple, it’s best practice to canonicalize your homepage as soon as possible. Whether you’re just setting up your website, or it’s been established for a while, this step is an important one not to miss as it lays the groundwork for your entire site to sit on.

The reason for canonicalizing your homepage?

Your home page is not just accessible at www.homepage.com – it can be seen at, http://homepage.com, www.homepage.com/index, and so on. This means that when someone is searching for your site, they could potentially land on lots of different variants of the same page. So, when someone is searching for your site, which page do you want them to be directed to? Setting a canonical tag pushes those people to the right page.

This trick not only eases the customer journey as they’re not encountering different permutations of homepage extensions every time they search for you, but it also helps to ease SEO problems caused by duplicate content. Because of the canonical tag, crawlers don’t have to index reams of the same page under different extensions, which in turn positively affects your search engine ranking and helps users land on the correct page, the first time.

Near-duplicate content

It’s good practice to add a canonical tag to exact duplicate pages, but what should you do when content is almost the same, but not quite?

Moz suggests you should proceed with caution because you could end up confusing the crawlers and be left with pages that can’t be ranked in the SERPs or having tags ignored completely. 

For example, you might create different product pages in different currencies but want all of these pages to rank individually because they’re targeting separate audiences. According to Moz, if you add a canonical tag to the page with your default currency, search engines might not crawl and rank any of the other versions of that product page. 

Here, it’s at your discretion whether or not to use a tag. But if you think a page is unique enough to be indexed as a separate entity to the default page, do nothing – unless you don’t mind the other versions of that page not being visible in the SERPs.

Changing your domain or URL permanently

If you’ve recently moved to a better cheap web host and want to transfer all your content permanently to a different URL, rather than canonical tags, it’s best to complete a 301 redirect of all duplicate pages.

Whether you’re moving from http to https, or changing your website name entirely, this is a good fix that’s especially valuable when customers don’t necessarily know your new domain just yet. When someone searches for www.oldwebsite.com, they’ll be automatically redirected to www.newwebsite.com, which stops you from missing out on traffic and keeps your regular visitors looking you up and landing where you want them to.
This is the most efficient and effective way of transferring your web content in one fell swoop rather than archiving the content and starting afresh on your new domain.

When to use the noindex tag

When you’re considering using a canonical tag, ask yourself whether you have reason to use the noindex tag instead. The noindex tag prevents crawlers from indexing a particular page on your website and is a quick and easy way to remove duplicate content from search results. 

According to the Search Engine Journal, if your site has hundreds of pages with similar content, noindex can help reduce the number of time crawlers spend indexing it, which will optimize crawl spend and help to boost your SEO performance. This can be good when you have lots of archived or out of date content that you want to keep in your CMS in the backstage. Using a noindex tag in this situation is far better than adding a canonical tag – but only if you definitely don’t want the content available in the SERPs.

But, be careful. Misusing noindex can affect your organic traffic. So, only use it if you’re sure you don’t want a page indexed, know a canonical tag isn’t appropriate, and don’t have an alternative system for archiving old content.

Canonical tags cause a lot of debate in the SEO world, with many different sources offering case studies that demonstrate that one use is preferable to another in their opinion in a whole host of scenarios. So, it can be tough to know what choice to make.

The best practice?

If you’re not sure, either don’t use canonicals at all or test their viability through trial and error – but ensure you use other tools such as a 301 redirect or noindex tags with the utmost dexterity due to their powerful consequences. Whenever you change something major on your website, you should track your metrics before and after and compare the result to see if you’ve got what you wanted or just made everything worse. From there, you can decide what’s best for your SEO rankings and website.

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Author Info

I’m Lucy Farrington-Smith, a 27-year-old freelance writer. I started out as an actor before I put the scripts down and chose to write my own words instead of saying someone else’s. One Master’s in Creative Writing and many coffee cups later; you can now find my bylines on HuffPost, Metro.co.uk, and my own website www.lucywrites.co