Canonical URL
An HTML tag that tells search engines which version of a page is the 'official' one to index.
A canonical URL (specified with a rel="canonical" tag) tells search engines which version of a page is the master copy. When the same content is accessible at multiple URLs, the canonical tag points to the preferred version.
This happens more often than you'd think. A product page might be reachable via the main URL, a URL with tracking parameters, a print-friendly version, and a URL with session IDs. That's four URLs with identical content. Without a canonical tag, search engines might index all four and split your ranking signals between them.
The canonical tag goes in the <head> section of your HTML: <link rel="canonical" href="https://example.com/preferred-url" />. It's a hint to search engines, not a directive — Google usually follows it but doesn't have to.
Self-referencing canonicals (where a page's canonical points to itself) are considered best practice. They prevent issues with URL parameters and ensure every page explicitly declares its preferred URL.
Why It Matters for SEO
Without canonical tags, search engines may index duplicate versions of your content, diluting your ranking power across multiple URLs. This is one of the most common technical SEO issues. Proper canonicalization consolidates link equity to a single URL.
🔍 How to Check This
AuditMySite's SEO Scanner checks for missing or incorrect canonical tags across your entire site.
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