Self-organization is a great concept for building scalable systems consisting of a huge number of subsystems. The primary objectives are improved scalability and dynamic adaptation to changing environmental conditions. Until now, many selforganization methods have been developed for communication networks in general and ad hoc networks in particular. Nevertheless, the term self-organization is still often misunderstood or misused. This paper contributes to the networking community by providing a better understanding of self-organization mechanisms focusing especially on the applicability in ad hoc and sensor networks. The main contributions of this paper are a clarification of the term self-organization and a categorization of self-organization methods. Additionally, well-known protocols in ad hoc and sensor networks are classified and selected case studies are provided. Primarily, solutions for the medium access control and the network layer are analyzed and discussed. Finally, open ...