cdnjs is a free distributed JS library delivery service.
Express is a web application framework for Node.js, released as free and open-source software under the MIT License. It is designed for building web applications and APIs.
jQuery CDN is a way to include jQuery in your website without actually downloading and keeping it your website's folder.
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.
Materialize CSS is a front-end framework that helps developers create responsive and mobile-first web applications. It is based on Google's Material Design guidelines.
Open Graph is a protocol that is used to integrate any web page into the social graph.