AddThis is a social bookmarking service that can be integrated into a website with the use of a web widget.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Prototype is a JavaScript Framework that aims to ease development of web applications.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.