This lesson examines the specific institutions and rules governing the electricity market both at the EU level and at the national level. At the EU level, the process of integrating the electricity market in the EU is being studied. At national level, and in the light of EU law, the role of the Energy Regulatory Authority and the companies involved in the production, marketing, transmission, distribution of electricity are examined. The relationship between the companies involved in the vertical chain of activities which have as their object the production and exploitation of that energy is, on the one hand, the relations between electricity distribution and trading companies with the final consumer (industry and households) Secondly. At the cross-border level, emphasis is placed on trans-national electricity transmission networks and the compatibility and interconnection of networks of two or more countries.