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 program and the recently established international MSc program in Electric Power Engineering. As the title indicates, the book deals with both power system economics in general and the practical implementation and experience from the Nordic market. Some of the subjects covered include: restructuring/deregulation of the power supply system * grid access including tariffs and congestion management * generation planning * market modelling * ancillary services * regulation of grid monopolies.