Polymorphism is not only interesting in the context of basic science, understanding the concepts of intermolecular interactions, but the industry dealing with materials as well as with pharmaceuticals, has also a huge stake in this area. For materials, control over the solid state is crucial for their physical properties, e. g. conductivity or strength, while for pharmaceutically active compounds, the form of the solid state structure can determine its activity potential. Polymorphs possess different properties, for instance the solubility or the mechanical resistance can differ dramatically from one polymorph to the other – properties which can be crucial for their application. Hence, it is important to be able to control the formation of polymorphs and to understand their formation. Particularly for organic compounds, there seems to be a large number of polymorphs possible if for example many hydrogen bonds can be formed between the individual molecules. Thus, for many compounds and depending on the external conditions, there may just as well be still a number of polymorphs to be discovered – depending on how much time and energy is spent searching for them.