The discovery of the X(3872) at the beginning of this century led to a revival in hadron spectroscopy. In the following years a number of states, commonly referred to as XYZ states, have been found that seem to be at conflict with the interpretation as conventional QQbar mesons. This culminated in the discovery of the Zc(3900) at BES III in 2013. In this talk I will introduce the concept of Hadronic Molecules and show how it might provide an explanation for the nature of some of the XYZ states, in particular I will focus on the charmonia Y(4260) and Zc(3900). Further I will provide an outlook to the higher charmonium as well as the bottomonium region and show where additional molecular states can be expected.