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
Chrome for Android, since version 39 supports the "theme-color" meta tag to allow websites control the background color of the tab's UI header.
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.