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.
This site uses the viewport meta tag which means the content may be optimized for mobile content.
Google APIs are application programming interfaces developed by Google which allow communication with Google Services and their integration to other services.
PayPal is a American international e-commerce service that enables companies and individuals to send money and to accept payments without revealing any financial details.
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.
Google's hosted library for web fonts. Allows websites to choose and use fonts from a free, wide variety of fonts.