Websites using some form of Captcha technology on them.
Anti-bot CAPTCHA widget that helps digitize books by providing snippets of books for people to enter the text for. Owned by Google.
Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user’s browser and allows you to target specific browser functionality in your stylesheet.
This site uses the viewport meta tag which means the content may be optimized for mobile content.
A family of standard web feed formats used to publish frequently updated information like blog entries, news headlines, audio and video.
UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. It is the preferred encoding for web pages.
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.
A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred".
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
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.