The Special Issue of the IEEE Power and Energy Magazine (January/February 2015) is devoted to the unprecedented revolution of the European power sector which is facing tremendous changes and challenges to improve is sustainability and the security of supply as well as to implement the integration of the internal EU-28 energy market and its liberalization. Aging assets with the need for decommissioning and upgrading the entire electrical power infrastructure (generation, transmission, distribution and R&D activity) is also a considerable concern in the European energy landscape. Indeed, secure, sustainable, available, and affordable energy is fundamental to modern societies and to the well-being of citizens as well as for industry competitiveness. The European power system serves more than 500 million people distributed over a large territory, with an annual consumption of over 300 TWh. The corresponding generation portfolio is still composed primarily of traditional plants using fossil, hydroelectric and nuclear energies. The current high-voltage transmission grid is made of approximately 300,000 km of overhead lines and cables. It has historically been developed on a national basis with a limited number of interconnections at the boundaries of neighboring countries initially built for security support on the open market. The recent opening and expansion of cross – border markets has drastically modified this situation, leading to a fast and continuous increase in cross-border exchanges and emphasizing the need for a new infrastructure enabling a better European market integration. Distribution grids at medium and low voltages cover about 5 million km of lines and cables and are managed by about 5,000 distribution operators in all EU countries. In Europe, a large fraction of the PV and wind generation is connected a the distribution level, and this requires a major shift in the operation of distribution networks. To fulfil the European climate and energy policies, the electrical system is in a period of very fast and radical evolution with a very high development of renewable energies patterns as well as through economies of scale, but it is facing major challenges in planning, developing, and deploying the appropriate technology solutions to respond to the political objectives and support the convergence to a decarbonized and sustainable economy.