Define Canonical URL

[Paul Jameson]

A canonical URL is a URL that is the best indexed version. It does not contain any duplicate material which can be a problem when using inconsistent links as the same content can get indexed many times for different URLs and this can cause problems.

[ackerlee]

Canonical URL is the search engine friendly URL that you want the search engines to treat as authoritative. In other words, a canonical URL is the URL that you want visitors to see.

[samdorjey]

Canonicalization is the process of picking the best url when there are several choices, and it usually refers to home pages.