Google+ platform websites integration using the Google+ platform tag.
Let visitors recommend your content on Google Search and share it on Google+.
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
The Open Graph protocol enables any web page to become a rich object in a social graph, a open protocol supported by Facebook
Open graph title entity tag
Sites who has this tag are verfied by google to use WebMaster tools