Mobile Ad-hoc network (MANET) is a dynamic, self-organizing and self-configuring distributed wireless network that comprises of a collection of wireless mobile nodes communicating directly with each other without any fixed communication infrastructure or centralized administration. The path chosen for transferring the information from one node to another node is called routing and the protocols used are called routing protocols. The requirement of routing protocol is to send and receive information among the nodes with best suited path with the minimum delay. MANET works with radio waves without need of any central coordinating device. It is an autonomous network supporting dynamic topology. Having all these facility MANET also has its own demerits. These issues are related to security and its protocol. This book gives an idea of mobile Ad-hoc Network, Applications of MANET and its security issues.