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.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Simple parallax scrolling effect.
Popper is a positioning engine, its purpose is to calculate the position of an element to make it possible to position it near a given reference element.