In a free market economy, the law of supply and demand, rather than a central government, regulates production and labor. Companies sell goods and services at the highest price consumers are willing to pay, while workers earn the highest wages companies are willing to pay for their services. A purely capitalist economy is a free market economy; the profit motive drives all commerce and forces businesses to operate as efficiently as possible to avoid losing market share to competitors.
Command economies are marked by communist and socialist tendencies. The government controls the means of production and the distribution of wealth, dictating the prices of goods and services, and the wages workers receive.
Free market economies and command economies exist more as abstract concepts than as tangible realities; almost all of the world's economies feature elements of both systems. For example, while the U.S. allows companies to set prices, and workers negotiate wages, the government establishes parameters, such as minimum wages and antitrust laws, that must be followed.
Based on the 2017 Index of Economic Freedom, Hong Kong, with its extremely low tax rates, minimal regulations on businesses, and highly capitalist system of economics, ranks as 89.8% economically free, which is the highest in the world. Singapore ranks second and is 88.6% free. The country imposes no tariffs, and there are few restrictions on investments. Singapore also features strong private property rights.
Australia, which ranks as 81.0% free, also has very low tariffs and strong private property rights. The government provides businesses with lots of flexibility and does not constrict them with overly complicated regulations or licensing procedures.
New Zealand and Switzerland round out the top five, having 83.7% and 81.5% free economies, respectively.
The U.S., featuring the world's most-advanced financial markets, is 75.1% economically free, as of 2017. This number has decreased in recent years. While certain U.S. industries generate more government scrutiny than others, private companies, rather than the government, control most sectors. The country also practices free trade with much of the world.
The five countries with the least-free market economies are North Korea, Venezuela, Cuba, Republic of Congo, and Eritrea. (You might be interested in reading: What is the difference between a capitalist system and a free market system?)