The rapid development of wireless digital communication technology and the corresponding network software systems have created new horizons for communication beyond the Internet realising the connected society. Among them, the field of mobile ad hoc networking is experiencing unprecedented growth in its scale and application diversity. Without requiring the pre-existence of communication infrastructures, a temporary network can be established on demand and disappears when there is no need. Although some basic concepts have been identified and elaborated, the mobile ad hoc networking is still in its early stage of research and development. Multihop communication with dynamic topology caused by mobility poses interesting but unique challenges ranging from the network-layer connectivity problem to the link-layer capacity issue. And, it should not be considered as a natural extension of infrastructure-based networks, such as cellular networks and IEEE 802-11 networks, because it often leads to confusion and non-optimal design choices.