cdnjs is a free distributed JS library delivery service.
Contao is an open source CMS that allows you to create websites and scalable web applications.
GSAP is an animation library that allows you to create animations with JavaScript.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
jQuery is a JavaScript library which is a free, open-source software designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.