Most small sites I audit as a freelancer have canonical tags. Very few have correct canonical tags. And the bad ones rarely throw an error — they just quietly tell Google "don't index this page," and you find out three months later when a page you care about shows up in Search Console as "Alternate page with proper canonical tag" or "Duplicate, Google chose different canonical than user."

This post is about the practical middle ground: when a canonical tag genuinely helps a 20–200 page site, and when it's papering over a bug you should fix instead.

What a canonical tag actually does

<link rel="canonical" href="https://example.com/page/"> is a hint , not a directive. You're telling search engines: "if you find several versions of this content, this URL is the one I want shown."

Google weighs it alongside other signals: internal links, sitemaps, redirects, HTTPS, and which URL other sites link to. If those signals disagree with your canonical, Google may ignore it.…