Consider that market economy consists of an economic system in which the agents involved can act with little governmental interference, thus being a typically capitalist regime. Freedom is a central element in this type of economy, and free competition is what regulates the market in relation to established prices.
In turn, the production and consumption of goods and services occurs through the law of supply and demand, defined by sellers and buyers, respectively. In this type of economy, what motivates both sellers and buyers is precisely this element of supply and demand, in which products will be produced as demand is sought, and the common interest will be given by the interchange between economic value attributed to it.