In this book; Chapter 1 introduces about the field of Mobile Computing, presents a short history and challenges for research, and concludes with a market vision, which shows the potential of mobile technology. Chapter 2 follows mobile IP, the extension of the Internet Protocol (IP) into the mobile domain. Ad-hoc networks with their requirements for specific routing protocols are also covered. The subsequent layer, the transport layer, is covered in Chapter 2. This chapter discusses several approaches of adapting the current transmission control protocol (TCP), which is well known from the Internet, to the special requirements of mobile communication systems. Chapter 3 comprises the global system for mobile communications (GSM) as today's most successful public mobile phone system, cordless phone technology, trunked radios, and the future development with the universal mobile telecommunications system (UMTS). Chapter 4 follows the classical layers of communication systems and explains the basics of wireless technology from a computer science point of view. Topics in this chapter are signal propagation, multiplexing, and modulation. Profound electrical engineering knowledge is not required; however, it is necessary to comprehend the basic principles of wireless transmission to understand the design decisions of higher layer communication protocols and applications. Chapter 5 and 6 depicts that Ad hoc networks are a key to the evolution of wireless networks. They are typically composed of equal nodes that communicate over wireless links without any central control. Ad hoc wireless networks inherit the traditional problems of wireless and mobile communications, such as bandwidth optimization, power control, and transmission quality enhancement. Chapter 7 discusses handoff, which is the mechanism for transferring an ongoing call from one base station to another as a user moves through the coverage area of a cellular system. It must be fast and efficient to prevent the quality of service from degenerating to an unacceptable level. Chapter 8 reviews existing solutions to the location management problem. Chapter 9 introduces mobile number portability. We describe and analyze number portability routing mechanisms and their implementation costs. We first describe the Signaling Relay Function based solution for call-related and non-call-related routing. Chapter 10 surveys data management schemes in wireless mobile environments. Mobile computing can possibly be viewed as a variation of traditional distributed computing from the data management point of view. In general, there are two possible scenarios.