Meeting the demands of the rapid growth of wireless Internet subscribers and the development of the world location-based services (LBS) market, this volume introduces and comprehensively discusses various location based applications such as buddy finder and proximity and security services. The material is organized in three major sections: applications, technologies, and security. Written by experts from across the globe, the articles in each of the sections range from basic concepts to research grade material and include discussions of future directions. An extensive bibliography is included with each chapter.