Ceaseless acts of bargaining, haggling, buying, and selling happen around us all the time. Places where people gather to buy and sell goods and services emerge all around the world: in parts that are poor, in parts that are rich, at the old-fashioned market square, and in the modern digital world. We call these gatherings markets. Market forms vary from highly personalized services to commodities that are sold to millions of people at a time, from illicit goods to some of the most revered works of art. Originally, markets were meeting places that emerged at the frontier between villages as grounds where strangers could meet to trade. Trade generally did not emerge within a family or a tribe. 1 Today buyers no longer have to be physically present, although personal connections remain a crucial part of many markets. What small-scale and global markets have in common is the requirement of communication. Buyers and sellers must communicate and they must share some kind of a common understanding. 2 When they trade, buyers and sellers must share a system of signs and interpretations, an enforceable set of rules, customs, and laws governing contracts and an established system of property rights.We tend to take for granted that people in markets can buy low and sell high without much trouble in understanding or trusting one another. Markets appear so natural, that Adam Smith (1776/1981) considered that the propensity to 'truck, barter, and exchange' to be an innate part of human nature. It was the original sin of modern economics to proceed as if markets were natural phenomena. As if their