This paper reviews the study and use of the Wikipedia category system in the scientific research, adopting a systematic literature review approach, but considering the qualitative review of the content of a set of selected papers. Several types of work are identified, depending on the intrinsic study of the category system, or its use as a tool for the analysis of other documentary corpus different to Wikipedia. We conclude that the system of categories offers a valid classification scheme for different approaches and studies on the organization of knowledge in multiple contexts.