A pingback is one of four types of linkback methods for Web authors to request notification when somebody links to one of their documents. This enables authors to keep track of who is linking to, or referring to their articles.
Disqus is a networked community platform, reaching over 900 million people a month, 1.8 million registered communities, and over 300M active commenters. The service offers a networked comment system used to foster engagement and connect audiences from around the web. Disqus looks to make it very easy and rewarding for people ...
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
The average rating based on multiple ratings or reviews.
Any offered product or service. For example: a pair of shoes; a concert ticket; the rental of a car; a haircut; or an episode of a TV show streamed online.
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.
Sites who has this tag are verfied by google to use WebMaster tools