What is Canonical Tag?
The canonical tag (rel="canonical") is an HTML element in the head section that specifies the canonical (preferred) URL of a page. It solves the duplicate content problem when the same page is accessible under different URLs (e.g., with/without www, with/without trailing slash, with URL parameters). Example: <link rel="canonical" href="https://example.com/page/" />. The canonical tag is a hint, not a directive - Google can ignore it if inconsistent with other signals. Self-referencing canonicals (pointing to itself) are best practice. For paginated pages: Each page should reference itself, not page 1.
Key Points
- Prevents duplicate content problems
- Is a hint, not a directive
- Self-referencing canonicals as best practice
- Must be in <head>
- For pagination: each page to itself
- Cross-domain canonicals possible
Practical Example
“The product page has a canonical tag to the URL without tracking parameters.”