Canonical Tag
A canonical tag is a special HTML element used to tell search engines which version of a webpage is the preferred or "master" version when there are multiple pages with similar or identical content.
This tag helps avoid duplicate content issues, which can confuse search engines and dilute the SEO value of your pages. By setting a canonical tag, you signal which URL should be indexed and ranked in search results.
What does a canonical tag look like?
Here’s a basic example of a canonical tag in HTML:
<link rel="canonical" href="https://www.example.com/product-page" />
This line of code is placed inside the <head> section of the webpage. It tells search engines that this is the original or preferred URL, even if similar versions of the page exist.
Why canonical tags matter
Search engines aim to show users the best and most relevant version of a page. But websites often have duplicate or near-duplicate content due to:
- URL variations (e.g. with tracking parameters)
- HTTP vs. HTTPS versions
- www vs. non-www
- Pagination (e.g., /page/1, /page/2)
- Printer-friendly or mobile versions of the same page
- E-commerce filters or sorting options
Without a canonical tag, search engines may:
- Index multiple versions of the same content
- Split ranking signals across multiple URLs
- Choose the wrong page as the main one
- Reduce your chances of ranking well
A canonical tag consolidates SEO value by telling search engines where to assign credit.
How to use canonical tags correctly
- Use absolute URLs, not relative URLs.
✅ Correct:<link rel="canonical" href="https://example.com/page" />
❌ Incorrect:<link rel="canonical" href="/page" /> - Only point to one version per page — don’t include multiple canonical tags.
- Self-canonicalize every unique page — each page should have a canonical tag pointing to itself unless there’s a valid reason to point elsewhere.
- Avoid pointing to non-relevant pages — the canonical URL should have the same or very similar content.
- Use canonical tags with other SEO tools, like sitemaps, hreflang, and redirects, to avoid conflicts.
Canonical vs. 301 redirect
A canonical tag suggests the preferred version without actually redirecting users. A 301 redirect, on the other hand, permanently moves the user and the search engine to a different URL. Use a canonical tag when you want both versions accessible but only one indexed.
In summary, a canonical tag is a powerful SEO tool for managing duplicate content and ensuring your site’s authority isn’t diluted across multiple URLs. It helps search engines focus on the right version of a page, improving your chances of ranking higher and keeping your site structure clean and efficient.