This chapter provides an overview and a comprehensive discussion of problems, models, algorithms, and applications in a vast and growing literature of wireless sensor networks. Being a particular kind of ad hoc network, many power management and communication protocols may be designed specifically for those networks. The critical issues considered in these protocols are the objectives, the quality of communication, the energy consumption, and the network lifetime. Moreover, due to the large-scale aspect inherent in some applications, traditional exact solution approaches are not practical, so heuristics may be adopted instead. The chapter starts by introducing the main concepts in the design of WSN and a wide range of problems and applications. Basic formulations and algorithms are also discussed, together with their benefits and drawbacks.