Canonical tag is an HTML element that tells search engines which version of a page is the preferred, authoritative one.
The canonical tag (<link rel="canonical" href="URL" />) is used to avoid duplicate content issues by indicating the primary version of a webpage. When multiple pages have similar or identical content (like product pages with URL parameters), the canonical tag helps search engines know which version to index and rank.
This tag is especially important for e-commerce sites, blog archives, and any website with dynamic URLs or content duplication.
Why Canonical Tags Matter in SEO:
- Avoids Duplicate Content Penalties – Prevents dilution of ranking signals across similar pages.
- Consolidates Link Equity – Ensures backlinks and ranking power go to the main URL.
- Improves Crawl Efficiency – Guides search engines to focus on indexing the right content.
- Clarifies URL Preferences – Helps site owners control which pages show up in search results.
Best Practices:
- Use a self-referencing canonical tag on every canonical page.
- Point non-preferred URLs (like tracking parameter versions) to the main canonical page.
- Avoid conflicting canonical tags and redirects.
- Only canonicalize pages with near-identical content—not completely different ones.
- Don’t rely solely on canonical tags—combine with proper redirects when needed.
Example:
If your product page has multiple URLs like example.com/product?color=blue and example.com/product?ref=email, you should canonicalize them to example.com/product.