cdnjs is a free distributed JS library delivery service.
Flask is a Python micro web framework ideal for rapidly constructing web applications, offering minimalism, flexibility, and modularity.
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.