Content Security Policy is best used as defense-in-depth, to reduce the harm caused by content injection attacks.
The Open Graph protocol enables any web page to become a rich object in a social graph, a open protocol supported by Facebook
When running in a browser on a mobile phone, "format-detection" meta tag determines whether or not telephone numbers in the HTML content will appear as hypertext links. The user can click a link with a telephone number to initiate a phone call to that phone number.
Indicates that the site provides an interface specifically for searching the document and its related resources.
A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred".