Google+ platform websites integration using the Google+ platform tag.
Apps that link to your content can then use this metadata to deep-link into your app, take users to an app store to download the app, or take them directly to the web to view the content.
Open graph description entity tag
When running in a browser on a mobile phone, "format-detection" meta tag determines whether or not telephone numbers in the HTML content will appear as hypertext links. The user can click a link with a telephone number to initiate a phone call to that phone number.