cdnjs is a free distributed JS library delivery service.
jQuery CDN is a way to include jQuery in your website without actually downloading and keeping it your website's folder.
jQuery Modal is an overlay dialog box or in other words, a popup window that is made to display on the top or 'overlayed' on the current page.
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.
LiteSpeed is a high-scalability web server.