Canonical URL

A canonical URL is specified using the rel="canonical" link element in a page's HTML head section. It instructs search engines to treat a particular URL as the authoritative version of a page, consolidating ranking signals from duplicate or similar pages into one preferred URL. This prevents duplicate content issues that can dilute your search visibility.

Canonical tags are essential in many common scenarios. E-commerce sites often have the same product accessible through multiple URL paths or with different query parameters for sorting and filtering. Content management systems may generate duplicate pages with and without trailing slashes, or with www and non-www variations. Without canonical tags, search engines must guess which version to index, potentially splitting link equity across multiple URLs.

Implementing canonical URLs correctly requires identifying all duplicate and near-duplicate pages on your site and selecting the preferred version for each group. The canonical URL should be self-referencing on the preferred page and cross-referencing on duplicate pages. It is also important to ensure canonical tags are consistent with other signals like internal links, sitemaps, and hreflang tags.