Money is weird Easy to understand, harder to ignore..
No, seriously. You can't eat it. In practice, think about it. You hand someone a piece of paper — or more likely, tap your phone against a reader — and they give you coffee, rent, a used car, a stake in a company. Day to day, that paper has no intrinsic value. You can't build shelter with it. Burn it and you get a few seconds of warmth, max.
Yet the entire modern world runs on it.
How does that work? And the short answer: money isn't a thing. Miss one, and the system starts to wobble. And like any technology, it has to do specific jobs to be useful. But economists have spent centuries arguing about the details, but they mostly agree on three core functions. That said, it's a social technology. Miss two, and you don't have money — you have a collectible, or a speculative asset, or a very inefficient barter token It's one of those things that adds up..
Let's break down what those three functions actually are, why they matter, and what happens when they stop working The details matter here..
What Are the Three Functions of Money
Every economics textbook lists them in the same order: medium of exchange, unit of account, store of value. Sounds clean. In practice, they're deeply intertwined — and the boundaries get messy fast And it works..
Medium of exchange is the one everyone intuitively gets. It's the "I give you this, you give me that" function. Money sits in the middle of every transaction so you don't have to find a chicken farmer who also happens to need web design services.
Unit of account is the measuring stick. It's how we price things. A sandwich is $8. A laptop is $1,200. Your labor is $45/hour. Without a common denominator, you'd need to know the exchange rate between every pair of goods in the economy. Sandwiches per laptop. Haircuts per gallon of gas. The combinatorial explosion would be paralyzing Surprisingly effective..
Store of value is the time machine. It lets you move purchasing power from today to tomorrow — or ten years from now. You work in July, get paid in dollars, and spend those dollars in December. Or you save for a down payment. Or retirement. This function is what makes planning possible Small thing, real impact..
Here's the thing most intros skip: these aren't equal. A thing can be a decent store of value but a terrible medium of exchange (gold bars, real estate, that mint-condition Pikachu card). Because of that, a thing can be a great medium of exchange but a lousy store of value (hyperinflationary currency, airline miles that expire). The magic of modern fiat money is that it does all three well enough, simultaneously, for billions of people.
Some disagree here. Fair enough.
Why These Functions Matter (Why People Care)
You might be thinking: okay, textbook definitions. Why should I care?
Because when one function degrades, you feel it. Not as an abstract concept — in your grocery bill, your savings, your ability to plan That alone is useful..
Take Venezuela in the 2010s. That's why prices changed so fast that menus had to be rewritten daily. Useless. And holding bolívars overnight meant losing real purchasing power. That said, as a unit of account? But as a store of value? The bolívar was still a medium of exchange — people used it to buy bread right now. The currency technically existed, but it stopped being money in any meaningful sense.
Or look at Bitcoin. Phenomenal store of value narrative (debatable in practice, but the narrative drives behavior). Terrible medium of exchange — slow, volatile fees, irreversible transactions, limited throughput. Clunky unit of account — nobody prices their rent in BTC because next month that rent might be 0.03 BTC or 0.And 08 BTC. It functions as an asset, not as money.
The three functions aren't academic. That's why they're the load-bearing walls of your financial life. When they hold, you don't notice them. When they crack, everything gets harder.
How Each Function Works in Practice
Medium of Exchange: The Lubricant of Trade
Barter doesn't scale. Because of that, the "double coincidence of wants" problem is real: you need someone who has what you want and wants what you have. Money solves this by being the thing everyone wants — not for itself, but for what it can become.
In practice, this means:
- Acceptability: The grocer takes your dollars. - Portability: A phone weighs less than a sack of grain. Which means the landlord takes your transfer. But ledger entries survive forever unless the system collapses. The freelancer takes your Venmo. - Fungibility: Your $20 bill is interchangeable with my $20 bill. - Durability: Coins last decades. You don't need to hand over a cow and get change in chickens. But 50 for coffee. Banknotes survive washing machines (sometimes). Universal acceptance is what makes it money instead of a gift card. Digital entries weigh nothing.
- Divisibility: You can pay $3.No need to inspect serial numbers or provenance.
Some disagree here. Fair enough Practical, not theoretical..
The medium-of-exchange function is why network effects dominate. So the more people accept it, the more useful it becomes, the more people accept it. A currency used by 330 million Americans is the dollar. A currency used by 10 people is a curiosity. That's why displacing an entrenched medium of exchange is brutally hard — you're not fighting technology, you're fighting coordination Not complicated — just consistent. But it adds up..
Unit of Account: The Common Language of Value
This is the invisible function. You don't use the unit of account the way you use cash. You think in it.
Every price tag, every budget, every invoice, every tax return, every GDP figure — they're all expressed in the unit of account. It's the shared language that lets a complex economy coordinate without central planning Small thing, real impact..
Key properties:
- Stability: If the measuring stick stretches and shrinks daily, it's useless. Because of that, "
- Divisibility (again): Cents matter. Also, - Standardization: A dollar is a dollar is a dollar. You can't build a house with a ruler that changes length by the hour. No "premium dollars" vs "discount dollars.Millicents matter in high-frequency trading.
This is where a lot of people lose the thread.
Here's what most people miss: the unit of account doesn't have to be the same thing as the medium of exchange. Which means in high-inflation countries, people often price in dollars (unit of account) but pay in local currency (medium of exchange) at the day's exchange rate. In medieval Europe, accounts were kept in "pounds, shillings, and pence" — units that didn't even exist as physical coins for centuries. They were pure accounting constructs Took long enough..
The unit of account is the skeleton. Worth adding: the medium of exchange is the blood. You need both.
Store of Value: The Bridge Across Time
This is the function that gets the most attention —
and the one most prone to volatility.
If the medium of exchange is about space (moving value from point A to point B) and the unit of account is about logic (measuring value), the store of value is about time. It is the ability to take the effort you exert today and "freeze" it so that you can thaw it out and consume it a decade from now Most people skip this — try not to..
For a medium to function as a store of value, it must resist the two great enemies of wealth: inflation and decay.
- Scarcity: If the supply of the asset can be infinitely expanded by a central authority or a sudden discovery, its value evaporates. This is the fundamental tension between fiat currency and hard assets like gold.
- Liquidity: A store of value is useless if you can't turn it back into a medium of exchange quickly. A plot of land is a store of value, but you can't buy a sandwich with a square foot of it.
- Predictability: You need to know that the "frozen" effort you stored in 2024 will still have roughly the same purchasing power in 2034.
When a currency fails as a store of value, the social contract begins to fray. When people realize their labor is being "melted" by inflation, they stop saving, they stop investing in the long term, and they pivot toward "flight to quality" assets—moving from paper to gold, or from local currency to the US dollar, or from cash to Bitcoin It's one of those things that adds up. Surprisingly effective..
The Trinity in Motion
To see how these three functions interact, look at a simple transaction: a worker earns a wage.
- Unit of Account: The worker looks at their contract and sees they earn "$50 per hour." This is the mental benchmark.
- Medium of Exchange: The worker goes to a grocery store and hands over a $50 bill. The transaction is complete.
- Store of Value: The worker puts the remaining $40 in a savings account, hoping that when they retire, that $40 has grown enough to buy a meal.
If any one of these pillars cracks, the entire economic structure wobbles. If the medium of exchange becomes too heavy or difficult to use (lack of portability), trade slows. Here's the thing — if the unit of account becomes unstable (hyperinflation), planning becomes impossible. If the store of value fails (currency debasement), the future becomes unnavigable.
Quick note before moving on.
Conclusion
Money is not "stuff." It is not just the paper in your wallet or the numbers on a screen. Money is a technology—a sophisticated, multi-dimensional tool designed to solve the problem of human coordination across space and time Nothing fancy..
It is the ultimate social lubricant. By providing a universal way to measure value, a universal way to exchange it, and a universal way to preserve it, money allows strangers to cooperate, economies to scale, and civilization to build. We don't just use money to buy things; we use it to synchronize the desires and efforts of billions of people into a single, coherent system Not complicated — just consistent..
