cdnjs is a free distributed JS library delivery service.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
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.
Mobile-detect.js is a compact JavaScript library designed to detect devices by comparing patterns against a given User-Agent string.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.