A family of standard web feed formats used to publish frequently updated information like blog entries, news headlines, audio and video.
Open graph description entity tag
A WebSite is a set of related web pages and other items typically served from a single web domain and accessible via URLs.
A scheme.org entity that represents an article, such as a news article or piece of investigative report. Newspapers and magazines have articles of many different types and this is intended to cover them all.
Sites who has this tag are verfied by google to use WebMaster tools