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
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.
Google's hosted library for web fonts. Allows websites to choose and use fonts from a free, wide variety of fonts.
Typekit is the easiest way to use real fonts on the web. It's a subscription-based service for linking to high-quality Open Type fonts from some of the worlds best type foundries.