This book is written as a textbook for students of engineering at the Norwegian University of Science and Technology (NTNU). It is designed for the Power Markets course which is part of the Energy and environment master's programme and the recently established international MSc programme in Electric Power Engineering. As the title indicates, it deals with both power system economics in general and the practical implementation and experience from the Nordic market. Some of the subjects covered: Restructuring/deregulation of the power supply system; Grid access including tariffs and congestion management; Generation planning; Market modelling; Ancillary services; Regulation of grid monopolies. Although it is written primarily as a textbook for students, readers outside the universities may also find the book interesting. It deals with problems that have been subject of considerable attention in the power sector for some years and it addresses issues that are still relevant and important.