The contribution of the authors from EWI and Fraunhofer FIT and FIM is part of the reference work “Energieflexibilität in der deutschen Industrie: Ergebnisse aus dem Kopernikus-Projekt – Synchronisierte und energieadaptive Produktionstechnik zur flexiblen Ausrichtung von Industrieprozessen auf eine fluktuierende Energieversorgung (SynErgie)”. The book presents the most important results of the Kopernikus-Projekt SynErgie and illustrates findings for further developments in the field of industrial energy flexibility. The SynErgie research project, which is funded by the German Federal Ministry of Education and Research, is investigating how companies will be able to design their processes and company organization in the future in such a way that energy consumption can be flexibly adapted, at least in part, to the volatile energy supply from renewable energies. The chapter “Electricity markets and system services” is devoted to the basics of electricity market design and the legal framework, with reference to the application to industrial processes and potential obstacles to the participation of flexible demand processes.