What is a canonical tag?
A canonical tag (rel=”canonical”) is an HTML attribute that tells search engines which URL is the master version of a page when multiple URLs contain the same or similar content. It is placed in the head of the duplicate page and points to the original.
Why canonical tags matter
Without canonicals, search engines may split ranking signals across duplicate versions of a page, or index the wrong URL. Canonicals consolidate signals to one URL, prevent duplicate content penalties and make crawling more efficient.
When to use canonical tags
- HTTP vs HTTPS versions of the same page.
- URL parameters that generate identical content.
- Print-friendly versions of pages.
- Syndicated content that also appears on other domains.
Common mistakes
- Canonicalizing to a page that does not exist or redirects.
- Using canonicals on pages that should be noindexed instead.
- Conflicting signals: canonical pointing one way while internal links point another.
Related terms
How Social SEO Team can help
Our technical audits fix canonicalization and indexation issues. See our SEO services for a full technical review.