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SEO/AEO/GEO

Canonical URL

Canonical Tag | rel=canonical

Portrait of Lukas Horvath, co-founder of Roelu Studio
Lukas HorvathCo-founder

What is Canonical URL?

A canonical URL is the version of a web page that search engines should treat as the master copy when multiple URLs serve the same or similar content. Specified with a rel=canonical tag in the page's HTML head, it tells engines like Google: "this is the original, index this one, consolidate ranking signals here." Canonical tags prevent duplicate content from splitting authority across multiple URLs.

Why it matters

Duplicate content is everywhere. Product pages with filter parameters, blog posts accessible by category and tag, http and https versions, www and non-www, trailing slashes. Without canonical URLs, search engines see ten URLs and have to guess which one to rank. The authority that should belong to one page gets split across all of them. Nothing ranks. Canonical tags fix it in one line of HTML. Most CMSes set them automatically. The teams that ignore them spend months wondering why their pages won't rank.

How it works

Inside the head of each page, you add a tag: <link rel="canonical" href="https://yoursite.com/page" />. That tells search engines this URL is the canonical version. If users land on a duplicate — say the same page with a tracking parameter — the canonical tag still points to the clean URL, and search engines consolidate signals there. Most modern CMSes (Sanity, Contentful, WordPress) handle canonical URLs through built-in fields or plugins. For e-commerce sites with filter combinations, canonical tags are non-negotiable. Get them wrong and you fragment authority across dozens of URLs. Get them right and ranking signals stack on the page you actually want to rank.

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