This document discusses hybrid mobile applications. It begins by describing the major smartphone operating systems and types of smartphone apps, including native, web, and hybrid. It then focuses on hybrid apps, explaining that they are developed with HTML5, CSS, and JavaScript but can access native device features by being wrapped in a thin native container. Popular hybrid mobile platforms and frameworks are listed, including Cordova, PhoneGap, and Ionic, which is described in more detail. The document outlines the technologies used to develop apps with Ionic including Node.js, AngularJS, and Gulp/Grunt. It also provides an overview of setting up an Ionic development environment.