Summary form only given. In wireless ad hoc and sensor networks, building efficient and scalable protocols is a very challenging task due to the lack of infrastructure and the high dynamics. Geographic protocols, that take advantage of the location information of nodes, are very valuable in these environments. The state required to be maintained is minimum and the discovery overhead is low, in addition to the fast response to dynamics. In this paper, we present a state-of-the-art overview of geographic protocols providing basic functions such as geographic routing, geocasting, and geographic-based rendezvous mechanisms. We introduce also some of our work on assessing and improving the robustness of geographic protocols to nonideal realistic conditions corresponding to the real-world environments.