Canonical Tag Usage Guide
Problem
The canonical tag tells search engines which URL is the 'authoritative' version of a page. When the same content is accessible via multiple URLs (with/without www, HTTP/HTTPS, with parameters), missing canonical causes duplicate content issues.
Best Practices
1. Every page should have a canonical tag
2. Use absolute URLs for canonical
3. Self-referencing canonical is recommended
4. Ensure the canonical target returns 200 status
<link rel="canonical" href="https://www.example.com/page-url">Use Cases
- Same content with multiple URL versions
- Paginated content pointing to first page
- URLs with tracking parameters
- HTTP and HTTPS versions coexisting
- With/without www versions