LinkedIn Plugins are a way to drop LinkedIn functionality into websites.
Google+ platform websites integration using the Google+ platform tag.
The Tweet Button is a small widget which allows visitors to share content and connect on Twitter.
Let visitors recommend your content on Google Search and share it on Google+.
Sleek, intuitive, and powerful mobile first front-end framework for faster and easier web development.
Open graph description entity tag
Sites who has this tag are verfied by google to use WebMaster tools