The European Commission's Clean Energy for All Europeans package confirms the leading role that citizens and communities will play in the future energy system. Energy communities are legal entities voluntarily integrated by individuals or companies, aligned with the objectives of sustainable development, allow partners to achieve energy, economic, environmental and social benefits that promote the expansion of renewable energies, improve energy efficiency, contribute to the decarbonization and decentralization of the energy system. The dual role of each member, shareholder and end user guarantees the advantages of energy communities: they create a sustainable environment, increase social development, control energy by its members, reduce costs, promote the use of clean energy, and help in the fight against climate change. In this field, this work presents a review of the state of the art of energy communities in Europe: the legal framework of the main countries, the activities and organizational forms, the types of renewable energy, a comparison of European success stories and Guide to project an energy community.