A “canonical URL” is the preferred or “canonical” version of a web page specified by the website owner. It is used to indicate to search engines and other web-based tools which URL should be considered the authoritative source for a particular piece of content, in cases where the same content is accessible via multiple URLs.
For example, if a page is accessible via both www.example.com and example.com, the website owner can specify that the preferred version of the page is www.example.com. This will ensure that search engines and other web-based tools index and rank the content of the preferred URL, and not any duplicates that might exist on other URLs.
The use of a canonical URL helps to prevent duplicate content issues and ensures that search engines are able to properly index and rank a website’s content. By specifying a canonical URL, website owners can also improve the visibility and credibility of their site, as search engines are able to distinguish between the preferred and non-preferred versions of a page, and are able to associate all backlinks and social signals with the preferred URL.