The document discusses different methods for prototyping mobile apps, including wireframing tools like OmniGraffle and Keynote. It describes creating wireframes that identify the key screens and navigation of an app. The document provides an example app concept for a timers app and sketches sample wireframes for its features. It also discusses additional prototyping tools like Skala Preview, LiveView and Reflector that can be used to demonstrate prototypes on mobile devices.