SEO Glossary /

Canonical Tag

A canonical tag is an HTML tag that is used to specify the definitive, or canonical version of a web page. This tag is used to prioritize one web page over another that has duplicate content.

The purpose of the tag is to communicate to search engines which page is the primary, preferred version to index and rank. This helps prevent duplicate content issues.

In HTML, the canonical tag has the format:

<link rel="canonical" href="https://example.com/example-page">

The key aspects are:

  • Rel attribute is set to “canonical” – This defines the link purpose
  • Href attribute points to canonical URL – This specifies the canonical page that search engines should index

In summary, the canonical tag consolidates signals around one definitive URL for a page to improve SEO rankings and prevent content dilution. It indicates the “master” reference page.

Managing Canonical Tags

Here are some ways site owners typically manage canonical tags:

  • Use a site management system or CMS (like WordPress) that handles basic canonical tags automatically. Many CMS platforms will generate canonical tags automatically to help avoid duplicate content issues.
  • Manually add canonical tags – Site owners can add tags in the HTML header of their pages to manually specify the preferred/canonical URL. This allows managing on a per-page level.
  • Configure tags at the web server layer – Some web servers and frameworks provide options for configuring canonical tags at the global website layer for certain types of content. This allows central management.
  • Dynamically generate tags – For sites generating pages dynamically, canonical logic can be programmed into the site to insert canonical tags based on rules for different URLs and content. This allows flexibility for customized implementations.
  • Regularly review and update – As site content evolves over time, it is important to review canonical tags periodically to ensure accuracy and that they match up with the true canonical versions of different pages on your site.
  • Use a plugin or SEO tool – There are various SEO plugins and tools for many site platforms that can add canonical tags across your site or help manage them. These may give site owners more control over automatically applying canonical logic across groups of pages.

Managing Canonical Tags in WordPress With AIOSEO

The All in One SEO (AIOSEO) plugin includes a way for users to easily manage canonical URLs.

While WordPress can generate a canonical URL, All in One SEO provides advanced features for managing them. These include:

  • Specifying a custom canonical URL
  • Managing related pagination issues

Related:

The following SEO case studies feature smart use of canonical tags.