This report tries to give a general vision of the state of art of the task of definitional question answering, by describing the task, illustrating the current interest on it, pointing out its main evaluation methods and the competitions that include subtasks of definitional question answering. The generical architecture of definitional question answering systems is presented, along with a description of the main techniques applied in the resolution of this problem. Finally, most important results in the task are presented and the main conclusions are exposed.