Socialism is a political ideology and economic system that is characterized by social ownership and democratic control of the means of production (meaning either collective/public/cooperative ownership or citizen ownership of equity). There are various forms of socialism in both market and non-market forms, with non-market socialism substituting factor markets and money with engineering and technical criteria, and market socialism retaining the use of monetary prices and factor markets. By the 1920s, social democracy and communism had become the two dominant political tendencies within the socialist movement, and democratic socialism would also develop as an important socialist ideology. Today, socialists head national governments in many parts of the world, and socialist parties are present (with varying degrees of power and influence) in nearly every democratic country around the world. Today, some socialists adopt causes such as feminism, liberal socialism, and environmentalism.