What is money?

Take a ten dollar note out of a wallet and look at it. It is a piece of plastic. You cannot eat it, wear it or live in it. And yet almost anyone on Earth will hand you real things in exchange for it. Understanding why is the first step in understanding all of finance.

Money is a shared agreement

Before money, people swapped goods directly. A farmer with extra wheat who wanted shoes had to find a shoemaker who happened to want wheat. That problem, called the double coincidence of wants, made trade slow and hard. Money fixes it. Everyone agrees to accept one common thing in exchange, so anyone can trade with anyone.

Think about how much that one change unlocks. The farmer no longer has to find a shoemaker who wants wheat. He sells his wheat to whoever wants wheat, takes the dollars, and buys shoes from whoever sells shoes. Every trade splits into two easy halves that no longer have to line up in the same place at the same time. That is the whole reason a modern economy, with millions of people making millions of different things, can function at all.

Through history that common thing has been shells, salt, silver and gold. Today it is mostly numbers in bank computers. Australian dollars work because the Australian government stands behind them and, more importantly, because every Australian believes everyone else will keep accepting them. Money runs on trust.

Why the trust does not collapse

You might wonder what stops that trust from simply evaporating one morning. Part of the answer is the government. Tax in Australia must be paid in Australian dollars, so every worker and business needs dollars whether they like them or not, and that steady demand gives the currency a floor. Dollars are also legal tender, which means the law recognises them as a valid way to settle a debt. But the deeper reason is circular in a way that turns out to be strong: you accept dollars because you know the shop will, the shop accepts them because it knows its suppliers will, and so on through the whole economy. Each person is trusting everyone else, and because everyone does, the trust holds.

A common belief is that somewhere in a vault sits a pile of gold equal to all the dollars in circulation, and that this is what makes the money real. That was roughly true a century ago, under what was called the gold standard, but no major currency works that way now. The dollar is not a claim on gold or on anything physical. It is what economists call fiat money, which means it counts as money because the government declares it so and because people accept it, and for no other reason. That sounds fragile, yet in practice it is the most flexible arrangement we have ever had.

The three jobs of money

• A medium of exchange: you can swap it for goods and services.
• A store of value: you can keep it and spend it later.
• A unit of account: it gives everything a price you can compare.

When something does those three jobs well, it works as money. When it does them badly, people stop using it. In countries where prices double every few months, workers rush to spend their pay the day they get it, because the money is failing at storing value. The third job is quieter but just as important: because everything carries a price in the same units, you can tell at a glance that a job paying $30 an hour beats one paying $24, or that one phone costs twice another. Without a shared unit, every comparison would be a puzzle.

Money in Australia

The Reserve Bank of Australia issues our notes and manages the system behind the dollar. Banks hold most of the money you will ever use as digital balances. Less than one in five dollars spent in Australia today is spent as physical cash, and the share keeps falling.

You can see the shift every time you tap a card at the school canteen or split a bill with friends by transfer. No note changes hands and no coin, just a message that moves a number from one account to another. The thing you are trusting is not the plastic of the card or the glass of the phone. It is the promise, honoured millions of times a day without anyone thinking about it, that the number is good and the next person will take it.

Because money is only ever worth what it can buy, its value is not fixed. It drifts over time as prices change, and understanding that drift is the subject of the inflation lesson later in this topic. For now the point is simpler: the dollar in your pocket is a shared promise, not a fixed lump of value.