Research on social robots is mainly comprised of research into algorithmic problems in order to expand a robot´s capabilities to improve communication with human beings. Also, a large body of research concentrates on the appearance, i.e. aesthetic form of social robots. However, only little reference to their definition is made. In this paper we argue that form, function, and context have to be taken systematically into account in order to develop a model to help us understand social robots. Therefore, we address the questions: What is a social robot, what are the interdisciplinary research aspects of social robotics, and how are these different aspects interlinked? In order to present a comprehensive and concise overview of the various aspects we present a framework for a definition towards social robots.