Book excerpt: This is a special issue of ECS Transactions published by ECS in memory of Volker Lehmann and Vitali Parkhutik, two key scientists in the field of porous semiconductors who recently passed away. Topics in this issue aim at a more detailed understanding of growth mechanisms and the physical and chemical properties of all types of porous semiconductors. The papers address research in the various sub-fields of porous semiconductors such as semiconductor electrochemistry, deposition into pores, matrix materials, optical spectroscopy and transdisciplinary approaches to the topic as well as work relevant to the formation of advanced materials such as, for example, porous silicon, matrix composites and nanoclusters and their applications such as chemical and biological sensors.