Google+ platform websites integration using the Google+ platform tag.
Let visitors recommend your content on Google Search and share it on Google+.
This script is the defacto way to enable use of HTML5 sectioning elements in legacy Internet Explorer.
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
Sites who has this tag are verfied by google to use WebMaster tools