The document discusses building hybrid mobile applications using HTML5 and JavaScript. It recommends using frameworks like Apache Cordova, Ember.js and NW.js to write code once that can run on multiple platforms. The document provides an example case study of building a GitHub organization viewer app with Ember.js that could be deployed to mobile, desktop and the web using these technologies. It outlines setting up models, routes, APIs and responsive design for the app and "hybridifying" it to run on different devices and platforms.