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What is "URL canonicalization"?

SEOMiddle~1 min read
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URL canonicalization is the process of choosing the primary (canonical) version of a page when the same content is available at several different addresses. The goal is to show search engines which URL to treat as the main one, so duplicates don't appear and the page's link equity doesn't get diluted.

Why this is needed at all

The same content can be accessible at different addresses, for example:

javascript
example.com/page example.com/page?utm=123 example.com/page/ www.example.com/page

To a search engine, these are different URLs, which means duplicates. As a result:

  • search ranking gets worse;
  • link equity gets "spread thin";
  • there can be uniqueness issues.

The solution is to specify the canonical address using a tag:

html
<link rel="canonical" href="https://example.com/page">

Then the search engine understands: the main version is the one in canonical, and the rest should be treated as secondary.

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