Network Simulation is most sought to research field and is an integral part of many research projects today including commercial applications, and academic research as well. The Networking and communications domain starts from finding friends on social networking sites to medical diagnosis to smart cities implemenataion and sensors also and even for satellite processing. In this book, we have made an honest effort to make the concepts of network simulation easy and also give basics programs in NS2 simulator right from the installation part. As the real-time application of networking and communications is endless but the basics concepts and algorithms are discussed by us using NS2 simulator so that from graduate students to researchers can get benefited with this.