What is Canonicalization?

Canonicalization is the process of selecting the preferred version of a set of duplicate or similar pages for indexing by search engines. It tells search engines which URL should be considered the “master” version when multiple URLs contain the same or very similar content.

This is typically achieved using a canonical tag (<link rel="canonical" href="https://example.com/page">) placed in the HTML header of a webpage.

Why Canonicalization Matters

Without canonicalization, search engines may treat duplicate URLs as separate pages, splitting link equity and possibly indexing the wrong version. This can dilute search rankings and confuse crawlers, especially on large or dynamic websites.

Benefits of canonicalization include:

  • Ensuring consistent indexing of preferred URLs
  • Consolidating link signals to one page
  • Preventing duplicate content issues
  • Improving crawl efficiency
  • Strengthening SEO performance

It is especially useful for eCommerce sites, content syndication, and any site with multiple URL variations for the same content.

Example in Use

A blog post might be accessible via both example.com/blog/post-title and example.com/post-title. By placing a canonical tag on both versions pointing to the preferred URL, you tell search engines which version to prioritise in indexing and ranking.

Canonical tags can also be used across domains when republishing content or working with partners.

Related Terms

  • Canonical Tag
  • Duplicate Content
  • Crawling
  • Indexing
  • Technical SEO
Bryn Roberts

Bryn has 10+ years in marketing and 20 in business development, helping businesses grow through strategy, creativity, and cross-industry insight. He’s helped companies across telecom, entertainment, and events.