If we each have a boxed lunch with the same sandwich, chips, a pickle, and a cookie, why would we consider trading items? Perhaps I prefer chips and you prefer cookies. Maybe I’ll give you my cookie for your chips. Now both of us are happier with our lunches. This is one example of how exchange can make people better off even without increasing the total amount of wealth. Exchange helps correct mistakes in allocation and it makes everyone involved happier. Professor Michael C. Munger offers a few examples of how exchange can make people happier whether people have the same preferences or different preferences, the same stuff to start with or different stuff. The ability to make people better off by simple exchange may seem like magic, Munger says, but it’s just markets.