LinkedIn Plugins are a way to drop LinkedIn functionality into websites.
Google+ platform websites integration using the Google+ platform tag.
Facebook Connect allow users to connect their Facebook identity, friends and, privacy to any website. Facebook Connect is Facebook's first attempt to allow access to Facebook user data outside of Facebook itself. The company is describing it as giving third party applications access to much of the same data as Facebook applicat...
This site uses the viewport meta tag which means the content may be optimized for mobile content.
Content Security Policy is best used as defense-in-depth, to reduce the harm caused by content injection attacks.
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
The http-equiv attribute provides an HTTP header for the information/value of the content attribute. The http-equiv attribute can be used to simulate an HTTP response header.
A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred".