Chosen is a jQuery plugin that makes long, unwieldy select boxes much more user-friendly.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Query Migrate is a javascript library that allows you to preserve the compatibility of your jQuery code developed for versions of jQuery older than 1.9.
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 UI is a collection of GUI widgets, animated visual effects, and themes implemented with jQuery, Cascading Style Sheets, and HTML.
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.
PHP is a general-purpose scripting language used for web development.