Canonicalization is the process of selecting the main, or “canonical,” URL for a piece of content. The canonical URL is the one that Google considers the most representative out of a set of duplicate pages. This helps Google show only one version of the same content in its search results, a process often called deduplication.

There are several reasons why a website might have duplicate content:

• Region Variants: Content for different regions (like the USA and the UK) that is accessible from different URLs but has the same information.
• Device Variants: Pages with both mobile and desktop versions.
• Protocol Variants: Different versions of the site using HTTP and HTTPS.
• Site Functions: The same category page showing different results due to sorting and filtering options.
• Accidental Variants: A demo version of the site that was accidentally left accessible to search engines.