Crypto from zero / 01
Money is a
scoreboard.
A small story about what makes a trade possible.
Imagine you’ve caught a fish. You take it to the baker, hoping to trade it for a loaf of bread.
There’s one problem.
“I already have fish,” she says.
You have something useful. So does she. But you still go home hungry.
Trading one good or service directly for another is called barter. It works when each person wants what the other offers. Here, that match is missing.
Now imagine the people in this market accept the same coins. You sell your fish to someone who wants it, then take those coins to the baker.
She accepts them because she expects to spend them with someone else. She can buy flour without finding a miller who needs bread.
You no longer need to want each other’s things.
The coins haven’t made more fish or bread. They’ve made it easier for those things to change hands.
One familiar thing
Three useful jobs.
You already use money in three ways, even if you’ve never given them names.
Money lets you pay for the bread, compare its price with other things, and save some spending power for another day.
That last job has a limit. Keeping the same number of coins doesn’t guarantee you can buy the same amount later. If prices rise, those coins buy less.
So money and the things it can buy are different. You can count the money in your pocket. What it will buy depends on prices.
From a coin to a number
What if no cash moves?
Back at the bakery, you tap your phone to pay. The baker hands you the bread. No coins pass between you.
Instead, records change.
Your bank balance is a record of money the bank owes you. That recorded amount is called a bank deposit. You can use it to make payments.
For a small example, imagine you and the baker use the same bank. You have 40 units. She has 10. You pay her 10 for the bread. There’s no fee and no borrowing in this example.
Your balance falls by 10. Hers rises by 10. The total across these two accounts stays at 50. This payment moves existing deposit money between you.
A record of balances and transactions like this is called a ledger. Real banking uses more detailed records, and payments between different banks involve extra steps.
Here’s the part to hold on to: a payment can work through a change in records. It doesn’t require a banknote to travel from one pocket to another.
The record needs rules
Who can change the score?
Imagine a stranger asks the bank to take 10 from your account. The numbers might add up perfectly. The payment still shouldn’t happen.
Before changing the record, the bank needs to check that the instruction is authorized and the payment meets its rules. In our example, you also need enough money to pay.
Checks can fail. Mistakes and fraud happen. A useful payment system also needs records people can review and a way to investigate and correct errors.
That gives you three questions to carry into the course: Who can request a change? What makes it valid? How can a mistake be put right?
The idea to keep
The form can change.
The jobs remain.
Money helps people trade, compare prices, and carry spending power into the future. It can take the form of cash or a recorded bank deposit.
When payments change records, those records need rules people can rely on.
Next, you’ll look at what makes something good at being money. First, try the idea for yourself.