Introduction

We use money every day. We earn it, spend it, save it, invest it — and rarely stop to ask: what exactly is this thing that makes the world go round?

Today's currencies, such as the real and the dollar, are the result of a long evolution. The Portuguese word for money, dinheiro, comes from the Latin denarius, the most widely used silver coin in Rome, whose name came to mean any circulating medium [6]. Throughout history, many things have played the role of money: cacao beans in Mesoamerica [3], dried cod (stockfish) as a trade good and unit of value in Iceland and in medieval Norwegian commerce [4] and, in medieval Irish law, the cumal — a word that meant "enslaved woman" and became a unit of value [5].

Why do we accept a piece of printed paper in exchange for our work? Where did it come from? Why does it matter? This text traces the history of money — from direct exchange to cryptocurrencies — to arrive at a simple idea: money is not wealth itself. Money is a technology for recording and transferring wealth.