When you go shopping, you usually find all the products and services you are looking for, at prices that you are willing to pay. It is actually surprising that somehow merchants in cities as large as New York, Los Angeles and Chicago know what products to have in their stores and in what quantities. Adam Smith, the father of modern economics, described this situation by saying that the free market economy operates as if an "invisible hand" (the price system) was directing it.

What is the process through which the free market economy determines goods and services must be produced?

What about non-free market economies?