A market economy can be defined as an economic system. In this system, the economic decisions as well as the prices of services and goods, are defined by the many interactions that have the businsses, the markets and the people in any nation.
One of the characteristics of a market economy is that the government has little or non-intervention in the regulation of prices. It is the market, -supply and demand- that establishes the economic conditions.
The market forces in modern societies drive the activities in their economies. The only case when the government intervenes is when to generate stability in the markets.