Canonical Tag

A canonical tag (or rel='canonical') is an HTML element that tells search engines which version of a URL should be considered the 'master' copy when multiple pages have identical or very similar content. This helps prevent duplicate content issues that can dilute SEO value. For example, if a product appears under multiple URLs due to sorting or filtering parameters (e.g., ?color=blue vs ?color=red), the canonical tag points to the primary version. It can be implemented via HTML, HTTP headers (for non-HTML files like PDFs), or sitemap entries. Note: canonicalization is a hint, not a directive—Google may ignore it if it conflicts with other signals.