In the past few decades, a technological revolution has occurred that has changed the way we live in dramatic ways. This technological revolution is the result of the emergence and evolution of a wide variety of new wireless networking technologies. Now people using these technologies are able to access the network and control many applications at will with their handheld devices anywhere, anytime. Although these technologies have made a long lasting impact in the revolution, it has also opened up various challenging issues which are yet to be resolved to make them more efficient and cost-effective. Wireless technologies are used in mobile cellular networks, wireless access network, Mobile Adhoc Networks (MANET), Wireless Sensor Networks (WSNs), Wireless Mesh Networks (WMNs), Vehicular Adhoc Networks (VANETs) and more recently Internet of Things networks. For readability and understanding, we have divided this book into three sections. Part I will discuss about trends and challenges of emerging wireless networks. In Part II, recent and advanced applications based on wireless communications are discussed. In our last section, we focus on future internet systems such as Internet of Things and other Internet-based systems.