This document provides an overview of mobile application development. It discusses the history of mobile technology from the brick era to the current touch era. It describes the various layers of the mobile ecosystem including services, applications, platforms, operating systems, and networks. It provides details on popular mobile platforms like Java ME, Brew, Windows Mobile, and Android. It also discusses mobile networks standards including 2G, 2.5G, 3G and technologies like GSM, UMTS, EVDO and WiMAX.