A canonical tag (rel="canonical") is an HTML element that tells search engines which version of a page is the "master" or preferred version when duplicate or similar content exists at multiple URLs.
When to use canonical tags:
- Duplicate content on different URLs
- Print versions of pages
- URL parameters creating variants
- HTTP vs HTTPS versions
- WWW vs non-WWW versions
- Syndicated content
Canonical tag implementation: <link rel="canonical" href="https://example.com/preferred-page/" />
Common canonical mistakes:
- Pointing to non-indexable pages
- Creating canonical chains
- Inconsistent implementations
- Canonicalizing different content
Canonicals and AI visibility:
- Help AI understand which version to cite
- Consolidate authority signals
- Prevent dilution across duplicates
- Ensure accurate attribution
Proper canonical implementation ensures both search engines and AI systems reference the correct version of your content.