as the Internet and the cell-phone network, toward the ad hoc networks -wireless networks formed on the fly. The problems of ad-hoc networks are very tantalizing, they are exciting to work on and they have an interesting mathematical structure. Despite the technical challenges, the interests of the ad hoc networks kept on increasing, because they support mobility and are very well-suited for many difficult situations, such as rescue mission, military, vehicular communications, etc. All of traditional distributed computing theory deals with wired-network and those communication protocols have been studied for many years. This work presents a descriptive of the what, why and how of ad-hoc networks - the concept of ad hoc networks.