Money's Three Jobs

Why do we use money at all? Imagine a world without it. You make bread, you want shoes — so you have to find a shoemaker who happens to want bread right now. Economists call that the "double coincidence of wants," and it almost never happens. Trade grinds to a halt.

Money solves this by doing three jobs at once.

1. Medium of exchange

This is the big one. Money is the thing everyone agrees to accept, so you never need a perfect match. You sell bread for dollars to anyone who wants bread, then buy shoes with those dollars from anyone selling shoes. Money is the middle step that connects two trades that would never have lined up on their own. That's a medium of exchange.

2. Store of value

Bread rots in a week. Money doesn't (much). Because money holds its worth over time, you can earn it today and spend it next month. It lets you move value across time — that's a store of value, and it's the whole reason saving is even possible.

3. Unit of account

Money is also the ruler we measure value with — a unit of account. A backpack is "$40," an hour of work is "$15" — all priced in the same units, so you can compare wildly different things instantly. Without a shared unit, you'd have no way to know if a trade was fair.

When a job breaks

These jobs can fail. In countries with runaway inflation, money stops being a good store of value — prices double in days — so people rush to spend it the second they're paid, or switch to using something stable instead. That's how you know the three jobs aren't just trivia: when one breaks, daily life breaks with it.