The design and governance of electricity systems is highly dependent on country-specific factors, technological innovation and disruptions, and the evolution of economic theory, and countries face different challenges in the evolution of their electricity systems when they seek to change their generation mix and market structure. In developed economies, characterized by high generation capacity and falling demand, liberalized energy systems have emerged as the dominant (although not universal) model. In most LDCs and ODCs, however, electricity systems are neither served by a monopoly provider nor fully liberalized, but are situated between these extremes, and their domestic markets are characterized by insufficient generation capacity and rising demand. Virtually all developing countries have sought to allow private-sector participation either through concessions or power purchasing contracts, or through liberalization of the generation segment of electricity supply.