The Purpose of a Canonical Tag and How to Use it

Canonical tags—the term itself can be intimidating. Apart from the confusion and anxiety they stir up among non-technical digital  marketers and website operators, there is a great deal of apprehension around their use.

Even seasoned webmasters often walk on eggshells when working with canonical tags for fear of messing up link systems they’ve worked so hard to build.

For this reason—despite the benefits that canonical tagging offers not only to website administrators but also to users—many site owners have yet to fully utilize this strategy. Don’t let lack of knowledge regarding its purpose and proper implementation stop you from taking full advantage. Read on to understand what a canonical tag really is so you can see beyond the cloud of mystery and confusion that prevents many site operators and marketers from realizing its true benefits.


Let’s begin by defining what canonical tag is.

The world of canonical tagging revolves around duplicate and preferred content. The term “canonical” is actually from the root word ‘canon,’ which traces its origins to biblical or secular laws and rules that are used as standard for judgment. Later, this word was used to describe works of an author that is accepted as authentic. This is exactly what ‘canonical’ tags do. They help search engines identify and recognize duplicate content as they relate to the original page.

Furthermore, a canonical tag lets search engines know which page should be displayed in the search results. When dealing with two pages having duplicate or very similar content, adding a canonical tag tells the search engine which of the two pages is the master copy and which is the clone. This means that if you have duplicate pages (A and B) and you want the first (page A) to be recognized as the master page and it  should appear in the search results, adding a canonical tag to the latter (page B) will let search engines know that it is the copy and therefore must not appear in SERPs. This way, all traffic and SEO juice is given to the original page.

When and how should canonical tags be used?

While SEO experts differ in their views as to how and when canonical tags should be used, many agree that this SEO tool is most useful when dealing with the following scenarios:

  • Separating duplicate and original contentPerhaps one of the most common uses for canonical tags, identifying duplicate content is one clear strategy that everyone seems to agree upon. Add a canonical tag whenever and wherever there is duplicate content on your website.
  • Similar/close-to-original contentE-commerce sites are notorious for having multiple pages that contain very similar copy or content with but slight differences between them. Canonical tags help search engines focus on the original or main product page, therefore giving full search value to it and helping it rank higher as you eliminate the confusion on which page should be shown.
  • Self-referencing canonicalsThis is a hotly debated topic. Many SEO experts were also torn about self-referential tags until Google announced that self-referencing canonicals must always be used regardless whether or not a page is a known duplicate. This means that pages must always have a canonical tag pointing to itself. This is especially useful when there are multiple ways by which visitors can reach your site, such as,, and so forth. Adding a canonical tag to each of these pages lets search engines recognize that the URLs point to one page and this page is what should be indexed and shown in search results.

Adding canonical tags to your pages is a critical part of optimization mainly because duplicate content affects how your pages are indexed and ranked. Duplicate content impacts the relevancy of search results and ultimately your site traffic and bottom line. This said, canonical tags shouldn’t be seen as a magic wand that can instantly improve your search ranking and visibility. As a matter of fact, incorrect use can impact your overall performance negatively.

Contact SEOValley if you need help in determining whether your website can benefit from canonical tags and implementing this strategy.