What are the 4 types of economic systems?

We have studied the traditional economic system, of which there are very few today.

The command economic system is an extreme form where the government owns all the factors of production and makes all the decisions for the economy (i.e. the 3 basic questions).

In the pure market system there is no government involvement or regulation and market forces (i.e. prices and supply and demand) determine how the 3 basic questions are answered.

In reality all countries have a mixed form of economic system where there are elements of both market and command systems in varying degrees. In our mixed market system we find the private sector, public sector, volunteer sector, and an active underground economy.