Node.js is required throughout the book. PhoneGap and the Cordova command-line interface utilize Node.js and NPM. Android Development Tool (ADT) is required if you want to build and emulate PhoneGap applications on Android. To be able to develop for the iOS platform, Xcode is needed. Unlike ADT, which can be run on major operating systems (Windows, Linux, and OS X), Xcode can only be installed on Mac OS X.