Canonical URL

Canonical URL
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A canonical URL indicates the preferred URL you would like to display for a particular keyword or query. Canonicals can be used to resolve a variety of cannibalisation and duplicate content issues. Simply put, canonicals allow you to specify the URL/domain/version of a web page you would like search engines to index.

It is considered best practice to use canonicals, and in most cases, you should use a self-referencing canonical. This is where the canonical URL is pointing back to itself.

A canonical URL, or canonical tag as they are also known, needs to be specified. You can set the canonical tag using a rel=canonical tag or a rel=canonical HTTP header.

Common Uses of Canonicals

Some web resources can often be available at different domains/sub-domains and protocols such as:

In these instances, and with examples of URLs on multiple paths, correctly using a canonical tag prevents search engines from indexing a URL using the wrong format.

canonical, rel=canonical, canonical tag
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