Canonical URL
A canonical URL is the official or preferred version of a webpage that you want search engines to index and rank when there are multiple versions of the same or similar content. It’s the URL you designate as the authoritative source when duplicates exist.
Search engines often encounter duplicate content caused by tracking parameters, filters, pagination, or even slight variations in page URLs. A canonical URL helps solve this by telling search engines:
👉 “This is the one you should pay attention to.”
Example of a canonical URL in HTML
To define a canonical URL, you add a canonical tag in the <head> section of your HTML:
<link rel="canonical" href="https://www.example.com/product-page" />
This tells search engines that https://www.example.com/product-page is the primary version of the page.
Why canonical URLs matter
Duplicate content can cause several SEO issues:
- Search engines may split ranking signals across different versions of the same page.
- The wrong version of a page might appear in search results.
- Pages with valuable backlinks could lose SEO value if the canonical version isn't defined.
By setting a canonical URL, you help search engines:
- Consolidate link equity and ranking signals
- Choose the right version of a page to show in search results
- Improve crawl efficiency by avoiding redundant content
When to use canonical URLs
Canonical URLs are useful in many situations, such as:
- E-commerce sites with filtered or sorted product listings
- Duplicate pages with minor differences (e.g., currency or region)
- Tracking URLs with UTM parameters
- Content syndication where the same article appears on multiple domains
- Paginated content (e.g., blog page 1, page 2, etc.)
Best practices for canonical URLs
- Use absolute URLs, not relative ones (e.g., use
https://example.com/page, not/page) - Self-canonicalize every unique page — it should point to itself unless you intentionally want another version indexed
- Avoid conflicting signals — don’t use canonical tags that contradict redirects or hreflang tags
- Don’t canonicalize to unrelated pages — only canonicalize between pages with very similar content
Canonical URL vs. Redirect
- A canonical URL suggests the preferred version to search engines without changing what the user sees.
- A 301 redirect permanently sends both users and search engines to a different URL.
Use a canonical URL when you want multiple pages accessible to users but want one version prioritized for SEO. Use a 301 redirect when a page should be completely replaced.
In summary, a canonical URL helps manage duplicate content by telling search engines which version of a page should be indexed and ranked. It's a key part of technical SEO that helps consolidate authority, avoid confusion, and maintain better control over your site’s visibility.