Identifies administrators for a page which will be able publish data to your wall if you like any content within this page.
Open graph description entity tag
The Open Graph protocol enables any web page to become a rich object in a social graph, a open protocol supported by Facebook
A web page. Every web page is implicitly assumed to be declared to be of type WebPage, so the various properties about that webpage, such as breadcrumb may be used. We recommend explicit declaration if these properties are specified, but if they are found outside of an itemscope, they will be assumed to be about the page
A scheme.org entity that represents an organization such as a school, NGO, corporation, club, etc.
A scheme.org entity that represents a person (alive, dead, undead, or fictional).
Sites who has this tag are verfied by google to use WebMaster tools
A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred".