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Canonical Tags: A Beginner’s Guide

SEO
 

What is the Canonical Tag?

The canonical tag offers a practical solution to duplicate and preferred content problems.It is a rather unusual word, but etymologically speaking, it is appropriate. It is derived from canon, which originally referred to biblical or secular rules and laws, a standard for judgment. Later, it was used to refer to the works of a writer who had been accepted as authentic.

This last meaning is where it relates to the Internet, SEO, and search engines, helping search engines identify which is the original page in relation to duplicated content.

There are many legitimate reasons for duplicate content, particularly when it comes to system-generated URLs. These include:

  • Multiple URLs – particularly on eCommerce sites where URLs are system-generated and have filter options for price, color, rating, etc.
  • Session ID URLs – automatically generated by your system. The same appliescoloracking URLs, breadcrumb links, printer friendly versions, and permalinks in certain CMS.
  • HTTP, HTTPS & WWW – search engines sprinter-friendlyomain.com, http://mydomain.com, and https://www.mydomain.com are distinct pages and will crawl (and possibly index) them as such.
  • Case – users and most browsers treat upper and lower case the same, with the two largely interchangeable. The same is not necessarily true for search engines, so if your website mixes up matter in filenames and folder structure, you need to use the canonical tag.
  • Mobile URL – when using a special URL (typically m.mydomain.com) for the mobile version of your website.
  • Country URL – when using multiple country-specific URLs, the content largely remains the same, with only a few minor differences in country-specific details if the language is different, in this case, you want the search engines to return separate results.

In most of these instances, the content isn’t actually duplicated; these are multiple URLs serving up the same content. Duplication usually occurs when the actual content appears on multiple unique URLs (www.mydomain.com versus www.someotherdomain.co), often as a result of content syndication.

The canonical tag should be used in all these instances to tell search engines which is the original content, and which URL should be crawled, indexed and returned on SERPs.

Use of the canonical tag is not mandatory, and Matt Cutts has previously stated that duplicate content rarely results in a penalty unless it is spam or being used to manipulate rank. Google mostly ignores the exact content to avoid having a SERP cluttered with the same results from different URLs. If it doesn’t, the penalty you may suffer is a lower overall rank for all duplicate content.

Why Canonical Tags are Important for SEO

Duplicate content can appear on a website even if different variations of English (US, UK, or Canadian, for instance) are used, and they are often frowned upon by search engines. By using a canonical tag, your website instructs search engine algorithms to index the designated canonical URL instead of the page’s original URL. There are multiple benefits of doing so, including:

To avoid duplicate content instances:

Canonical tags are of immense value if your website has different pages with near-identical content. These tags act as an impactful deduplication tool if other versions of the same website are available. For instance, a website in American and British English may come across as a website with duplicate content, increasing the chances of getting penalized.

By strategically using canonical tags, you can prevent such unfortunate instances without compromising the website's integrity. Parameterized URLs have parameters linked to them for better tracking of different metrics, and they may confuse algorithms and bots. Canonical tags prevent parameterized URLs from coming across as duplicate content in the eyes of search engines.

To increase accessibility

It is common for your target audience to search for a website in different ways. For instance, www.yourdomain.com, yourdomain.com, www.yourdomain.com/index.html, and more are some ways your target audience can look up your website, and canonical tags consolidate the path to ensure its accessibility. Aside from this, canonical tags also make the web pages available without the use of Trailing Slashes (“/”) and with case sensitivity.

How to Implement Canonical Tags

To implement canonical tags, you will be required to include the rel="canonical" tag.

Before you implement canonical tags on your website, take into consideration where your website is located. For instance, the implementation of these tags will be different on Magento, WordPress, and Wix.

While you will be required to manually make changes to Magento (1 or 2) websites, WordPress offers the convenience of installing plugins like Yoast SEO Plugin, Rank Math, and OZ Canonical SEO Plugin. Meanwhile, Wix has a self-referencing canonical tag that can be edited directly on the website.

Some other ways to include canonical tags on your website:

  • For non-HTML documents, you can use rel="canonical" in HTTP Headers.
  • If there are duplicate pages on the website, you can consider redirecting duplicate pages to canonical pages.
  • Another best practice to try is listing canonical URLs in your sitemap.

With canonical tags, website owners can ensure they give a clear indication to search engines like Google about how their website should appear on SERP. They also prevent issues that can arise due to duplicate content.

Canonical Tags: SEO Best Practices

Incorrectly placed canonical tags can result in search engines ignoring your indicators. It can result in them discovering pages with identical content and labeling them as duplicate content.

The first thing to do when using the canonical tag is to decide which is the preferred URL and then add the following markup to the <head> section of the selected URL and all its variants:

<link rel="canonical" href="http://www.yourdomain.com/your-preferred-url/" />

NOTE:While both relative and absolute paths are acceptable, it is always best to use absolute paths.

The good news is that most CMSs have this built-in or, at the very least, have plugins available that automate most of the process. If you are not using a CMS, Google (and other search engines) have made it a little easier to manage certain functions, including:

If your site serves the same content on both HTTP and HTTPS and regardless of whether the www was included or not, you may want to consider setting a preferred domain via Webmaster Tools or a 301 redirect.

To avoid such complications, here are the best practices to take serious note of:

  • Use one canonical URL per page

To avoid confusing search engines, stick to using only one canonical URL for every page. Avoid adding multiple canonical tags in the HTML. If you are automating adding these tags, rechecking them will prevent overlapping.

When more than one rel=canonical tag is present, search engines tend to ignore them and proceed with what suits them the best. This happens because there are multiple original versions of the same page available. If you are adding rel="canonical" to the HTML, avoid adding it to the header. Modern content management systems offer the convenience of easier canonical tag and URL management.

  • Establish either non-WWW or WWW URLs

The non-WWW and WWW versions of a URL are seen as the same in search engines' eyes.

For instance,

Website A: https://yourdomain.com/

Website B: https://www.yourdomain.com/

Both websites will seem the same to search engines, and due to this, it becomes essential to use only one URL version throughout the website.

  • Use canonical tags that point to themselves

Though there are no compulsions to implement this, making canonical tags point themselves is always beneficial. By using self-referencing (rel=canonical) tags on main (original content) pages, you will indicate to search engines where to look when showing information during SERPs.

  • Opt for lowercase URLs

Search engines like Google are sensitive to using lower or upper case letters in the URLs. It is highly recommended that all the canonical URLs be kept in lowercase to prevent any disparity.

Also, as most people search in lowercase, maintaining the same for URLs will make your website more SEO-friendly. Variations in capitalization can create problems with the indexing of webpages.

  • Canonicalise any cross-domain duplicate content

Canonical tags can be used to reference your website’s main page from domains other than your website. If there is duplicate content present (due to republishing) on other websites, using these tags ensures your website is not getting penalised.

To achieve this, consider applying a self-referencing canonical tag on your original website and apply a canonical tag to the external web page that references the original content.

  • Use absolute URLs

An absolute URL has all the information needed to identify and locate a resource. It can be used instead of a relative URL.

For instance, this is the URL structure you should consider following:

<link rel="canonical" href="https://yourdomain.com/blog/" />

Instead of using,

<link rel="canonical" href="/blog/" />

A clear URL ensures that your web pages are easy to locate, increasing their visibility for search engines.

  • Specify trailing slash or non-trailing slash URLs

Trailing slashes have an influence on how web servers identify and process URLs. They also have an effect on how search engines perceive pages. It also increases the performance of your SEO efforts alongside the content delivery of the website.

Here’s what a URL with and without trailing slash looks like:

With trailing slash: https://yourdomain.com/

Without trailing slash: https://yourdomain.com

Improper use of trailing slash may be seen as two separate URLs by Google. To avoid this, ensure that your canonical URLs are correctly placed and that you use trailing slash appropriately.

Common Mistakes in Implementing the Canonical Tag

Canonical tags are a strong indication that your website gives search engines the ability to index your preferred versions of web pages among duplicate ones available. Due to this, it becomes essential to allocate rel=canonical links with care. Here are some common mistakes to avoid when implementing canonical tags on your website:

Setting the Home Page as the Preferred URL

There are times when your home page will be the preferred URL. If all your canonical pages point to your home page, you risk having none of your pages (aside from the ones that have been indexed) crawled and indexed by the search engines.

Using Multiple Canonical Links

Each page must only have one canonical link specified in the <head>; otherwise, they will all be ignored. This can occur without you even being aware due to faulty. Otherwise, use an SEO plugin or an improperly edited theme/template.

Placing rel=canonical in the <body>

As with multiple canonical links, if your canonical link appears anywhere but the <head>, it is ignored. Ideally, it should appear as early as possible in your <head> section to avoid any parsing issues.

Using Canonical Links on Paginated Results

SEO can become a little complicated when it comes to splitting content over multiple pages, although it is necessary to do this at times.

When doing this, it is advisable to use the rel=prev and rel=next tags instead of rel=canonical to ensure that each page is indexed. Alternatively, if you have also consolidated the content on a single “View All” page, you can rel=canonical to that page instead.

Using Canonical Links in Featured Articles

If your site includes a regularly updated “featured article” or “featured product,” you should avoid using the rel=canonical tag on this page specifically. Not doing so or implementing it incorrectly can result in this page being ignored and not showing up in search results.

Using Canonical Links Instead of 301 Redirects

Although on the surface, the functionality of a canonical link is quite similar to that of a 301 redirect, in terms of metrics, they are not. While they both tell search engines to treat multiple pages (or URLs) as a single page, a 301 redirects all traffic to a specific URL, and a canonical tag does not.

If your site structure has changed, then a 301 redirect is the preferred option since it will also correct bookmarks. If your site has duplicate content, but you need to measure traffic to each URL, use a canonical link for the benefit of the search engines.

Conclusion

Although a penalty for duplicate content is unlikely, having search engines index all of your same content affects the relevancy of their results and could also affect how your pages rank, ultimately affecting your site traffic and revenue. However, canonical tags are not a magic bullet that will automatically improve your site’s visibility; if anything, incorrect implementation of them could affect your overall rank.

If you haven’t introduced canonical tags to your site yet, you must first carefully consider the actual need (do you have duplicate content or multiple URLs pointing to the same content?) before drawing up a strategy on how to implement it and on what pages. If you have already introduced canonical tags, it may help to revisit the implementation to ensure it was all done correctly and that you aren’t hiding any pages that should be indexed. By taking care of these factors, you can significantly increase your website’s ranking potential.

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