What is a Canonical Tag?
A canonical tag is an HTML element (<link rel=”canonical” href=”…”>) used to indicate the preferred version of a webpage when multiple pages have identical or similar content. It tells search engines which version of the page should be treated as the original or “canonical” version.
This helps prevent duplicate content issues and ensures that link signals (like backlinks and authority) are consolidated to the chosen URL.
Why Canonical Tags Matter
Duplicate content can confuse search engines and dilute ranking signals across multiple pages. A canonical tag solves this by clearly pointing to the version that should be indexed and ranked.
Benefits of using canonical tags include:
- Avoiding duplicate content penalties
- Consolidating SEO value to a single URL
- Improving crawl efficiency
- Maintaining cleaner, more organised site structure
They are especially useful in e-commerce sites with filtered or paginated URLs, or when content is syndicated or republished.
Example in Use
An online shop has two pages showing the same product:
- https://example.com/product/red-shoes
- https://example.com/product/red-shoes?ref=homepage
Both pages show identical content, but the canonical tag on the second page points to the first URL, ensuring that search engines index only the preferred version.