Google+ platform websites integration using the Google+ platform tag.
Identifies administrators for a page which will be able publish data to your wall if you like any content within this page.
Let visitors recommend your content on Google Search and share it on Google+.
Allows a website to define how a page is rendered in Internet Explorer 8, allowing a website to decide to use IE7 style rendering over IE8 rendering.
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
Meta Keywords are a specific type of meta tag that appear in the HTML code of a Web page and help tell search engines what the topic of the page is.