Google APIs are application programming interfaces developed by Google which allow communication with Google Services and their integration to other services.
This site uses the viewport meta tag which means the content may be optimized for mobile content.
Using this tag you can set up your web app to have an application shortcut icon added to a device's homescreen, and have the app launch in full-screen "app mode".
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 descriptions are HTML attributes that provide concise explanations of the contents of web pages. Meta descriptions are commonly used on search engine result pages (SERPs) to display preview snippets for a given page.
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.
The Open Graph protocol enables any web page to become a rich object in a social graph, a open protocol supported by Facebook