This is an introductory course designed to present the core components of the industry. In the first part, we analyze the resources and the products around which the industries and the markets are developing. In the second part, the main actors in the energy sector, both state and private, are analyzed: the first regulate and the latter invest and operate. The first are distinguished in international and national (international organizations and national regulatory authorities) and the second in national and multinational companies. Among the two are state-owned companies that operate in addition to productive / commercial activity and regulatory authority. In the third part, the overall regulatory framework for energy will be analyzed at the international, EU and national level, with emphasis on the process of liberalization and integration of energy markets in the EU and Wider Europe. In this context, on the one hand, the development of the rules and institutions which are aiming to ensure free competition in the energy sector at the national and European level, on the other hand the mechanisms and tools for the integration of the energy institutional framework and the harmonization of the terms and conditions of the exercise of energy activities the operation of energy companies, industries and markets not only at EU level, but also in the wider Europe, which includes the EU’s border states with the countries neighboring with Europe, which are either transit states of EU-funded energy resources or energy producing states that provide energy to the EU.