A mobile ad hoc network is a collection of wireless nodes that can dynamically be set up anywhere and anytime without using any pre-existing network infrastructure. Ad hoc networking can be applied anywhere where, there is little or no communication infrastructure or the existing infrastructure is expensive or inconvenient to use. One of the motivation behind this activity is the need felt by people to communicate with computers or device in natural mode of communication in respect of diverse application. The book is an attempt to present the advances in the networking technology -both theory and practice. This book provides a comprehensive reference material for students, instructors, researchers, engineers, and other professionals in building their understanding of ad hoc and ubiquitous computing. Each chapter on a particular topic is written in a tutorial manner and the chapters are organized so that the topics covered are easy to understand.