Apache is a free and open-source cross-platform web server software.
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.
Lightbox is small javascript library used to overlay images on top of the current page.
Modernizr is a JavaScript library that detects the features available in a user's browser.
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.