This chapter includes a relative study of mobile ad-hoc networks (MANET), vehicular ad hoc networks (VANET), and Flying ad-hoc networks (FANET). The approaches and protocol applicable to MANET are equally applicable to VANET or FANET. Authors discuss several emerging application and the future trends of MANET, VANET, and FANET. The common attacks on ad hoc networks are also introduced. The chapter enhances the overall concepts relative to MANET, VANET, and FANET. Authors compare mobile ad-hoc networks (MANET), vehicular ad hoc networks (VANET), and flying ad-hoc networks (FANET) in all aspects with the help of several examples. The chapter includes a relative and detailed study of mobile ad-hoc networks (MANET), vehicular ad hoc networks (VANET), and Flying ad-hoc networks (FANET).