Mobile platform development has lately become a technological war zone with extremely dynamic and fluid movement, especially in the smart phone and tablet market space. This Synthesis lecture is a guide to the latest developments of the key mobile platforms that are shaping the mobile platform industry. The book covers the three currently dominant native platforms -- iOS, Android and Windows Phone -- along with the device-agnostic HTML5 mobile web platform. The lecture also covers location-based services (LBS) which can be considered as a platform in its own right. The lecture utilizes a sample application (TwitterSearch) that the authors show programmed on each of the platforms. Audiences who may benefit from this lecture include: (1) undergraduate and graduate students taking mobile computing classes or self-learning the mobile platform programmability road map; (2) academic and industrial researchers working on mobile computing R&D projects; (3) mobile app developers for a specific platform who may be curious about other platforms; (4) system integrator consultants and firms concerned with mobilizing businesses and enterprise apps; and (5) industries including health care, logistics, mobile workforce management, mobile commerce and payment systems and mobile search and advertisement.