Google Publisher Tag (GPT) is an ad tagging library with which you can dynamically build ad requests. GPT takes key details from you such as ad unit name, ad size, and custom targeting, builds the request, and displays the ad on web pages or mobile apps.
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 review of an item - for example, of a restaurant, movie, or store.
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