Technical SEO
What is Canonical (Canonical URL)?
Canonical is the meta tag (or header) telling Google which is the "official" URL when the same content exists at multiple URLs (parameters, www/non-www, http/https).
The <link rel="canonical" href="https://site.com/post"> tag prevents duplicate content: store filters, pagination, UTMs create different URLs for the same content. Canonical solves it by concentrating authority on the main URL.
Common mistake: canonical pointing to itself on a paginated page (?page=2). For pagination, either canonical to page 1 (preferred), or self-canonical + noindex.
Frequently asked questions
Does canonical count as a 301 redirect?
No. Canonical is a hint; 301 is a real redirect. Use canonical for light duplicates; 301 for permanent change.
Can canonical point to another domain?
Yes, it is "cross-domain canonical" — useful in syndication (published elsewhere, points to the original source).