This chapter studies the role played by money in the coordination process in a decentralized market economy. This type of economy consists of private and separate individuals (or economic agents), acting outside any collectively planned objective. This is the normal hypothesis of the major share of economic theories. But this type of hypothesis at the same time needs to consider the formation of a society comprising private individuals. As economic theory tries to explain how society works through quantified relationships between different decision/action units (individuals, businesses), which are supposed to be mainly driven by the search for identifiable economic profit, the coordination of the social set of individual free actions appears to be an existential question. It is an inevitable field of
analysis, not only for conceptual construction, but also to understand mechanisms observable in society.