Electricity and some hydrocarbon activities have also been categorized as a public service, and are consequently inherent to the social purpose of the State. The electricity and hydrocarbon sector are important elements of a national public policy, not only because of their key role in the economy but also because of the necessities they meet. In general terms, the regulatory framework in Colombia for electricity is integrated in several legal instruments. The Constitution regulates several aspects of the electricity industry. For instance, hydropower generation potential is public property belonging to the nation, and the Federation operates the electricity services and energy installations through a concession, permission or authorization. The marketing of energy projects is secured by long-term purchase agreements of energy. The Ministry of Mines and Energy is the authority in charge of planning and formulating public policies and advises the presidency on the formulation of public policies as well as coordinating with the different authorities.