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.
Python is an interpreted and general-purpose programming language.
PythonAnywhere is an online integrated development environment (IDE) and web hosting service (Platform as a service) based on the Python programming language.
Unpkg is a content delivery network for everything on npm.