Many technological processes and applications demand highly specific materials with tailored properties. Examples are high-energy density batteries for mobile information technology, materials resilient under awkward thermal, pressure, radiative, or chemical conditions (disposal of nuclear waste, shielding of spacecraft). The structure of highly specialised materials becomes more and more complex with an increasing number of boundary conditions for the properties aimed at. Physicists can do their share in the development of novel materials by providing information on the structure of complex materials and linking it with macroscopic materials' properties. This information will provide guidance as to where to look for new classes of materials for tomorrow's technology. In the module, various structural characterisation techniques are introduced, and their use for the investigation of some important structure-property relationships is demonstrated. The course is organised along some basic material classes, and some current applications are discussed.