Fiat currency is money that is worth something because a government declares it so.
Why it sounds harder than it is
Fiat is Latin for "let it be done". It is not an acronym, it is not a brand, and it has nothing to do with the car.
The word is marking one distinction and no more: money backed by a physical thing you could in principle demand, against money backed by a decision and a set of institutions. Australian dollars are the second kind. So are almost all currencies in daily use.
That is not a scandal and it is not a secret. It is a design choice, made a long time ago, never mentioned at school, and then discussed in a tone that suggests everyone else was told.
A concrete Australian example
Look at a twenty dollar note. It does not promise to pay you anything, and there is no vault somewhere holding something with your name on it.
It works at the checkout because the person behind the counter expects the next person to take it as well, and so does everyone in the chain behind them.
That shared expectation is the mechanism, and it holds up well for something you cannot see. The balance in your bank account works the same way and does not even have the paper.
What it is not
- Not fake, and not a trick. The value is conditional rather than absent, and almost everything in finance is conditional on something
- Not the same as digital money. Fiat describes what stands behind the currency, not what form it takes. The note in your wallet and the number in your account are both fiat
- Not unique to Australia. Nearly every currency you will meet works this way, which is why the word is a description rather than a criticism
- Not the same as inflation. Fiat is the design. Inflation is one thing that can happen inside it
Related
Next time someone calls money paper with a promise on it, the interesting question is not whether that is true. It is why it works anyway.