OPEC's official purpose, as quoted directly from its charter, is to "coordinate and unify the petroleum policies of its member countries and ensure the stabilization of oil markets, in order to secure an efficient, economic and regular supply of petroleum to consumers, a steady income to producers, and a fair return on capital for those investing in the petroleum industry." As such, it is an intergovernmental body whose members work together to coordinate petroleum outputs to the world market. However, since the members represent such a large part of world production, critics argue that OPEC in fact constitutes a cartel with market manipulation powers.