Canonical Links: In page and in HTTP header
Canonical link tags can be placed in either the page itself or in the HTTP header of your web server
When our indexing bots find a canonical link it removes the page that contains the link from the search results and allows the page that is in the canonical link to appear in the search results
In Page Example:
<link rel="canonical" href="">
In Http Header Example:
link "<>; rel="canonical""