Thanks for the post. I guess the only real non-fiat situation is where you barter. In other words, I give you three sheep for one month’s accommodation, or I give you 10 loaves of bread in exchange for 1 kg of coffee beans. Some people still do this to avoid tax I think. Actually I think I have done it too. You can exchange services too. Like I can say, OK, I will translate your website for you from German to English, if you give me a laser teeth whitening treatment.