A canonical URL tells search engines which version of a page should be treated as the primary one when multiple similar URLs exist.
Canonical tags help prevent duplicate content issues by consolidating ranking signals into a single preferred URL. Without canonicalisation, search engines may split authority across multiple versions of the same page.
Canonicals are commonly used for filtered URLs, pagination, tracking parameters, and similar content variations.
Correct canonical implementation helps preserve PageRank and ensures the correct page appears in search results.