What Money Actually Is
Before we can build digital money, we need a clear answer to a deceptively simple question: what is money, mechanically?
The three jobs of money
Section titled “The three jobs of money”Economists describe money by what it does:
- Medium of exchange — you accept it because you’re confident others will too. It removes the need for barter (the “double coincidence of wants”: a baker who wants shoes must find a shoemaker who wants bread).
- Store of value — it holds purchasing power across time, so you can sell today and buy later.
- Unit of account — it’s the ruler you measure prices with (“this costs 3 units”).
The deeper truth: money is a ledger
Section titled “The deeper truth: money is a ledger”Strip away the physical form and every monetary system is the same thing underneath: a record of who owns what, that a community agrees on. Money is a shared ledger.
- A bank database is literally a ledger — rows of balances.
- Even physical cash and gold are a ledger, just an implicit one: possession is the record. Holding the coin is the entry that says “this is mine.”
What makes money good
Section titled “What makes money good”Not every ledger token works well. Through history, the things that survived as money scored well on a set of properties. Here’s the scorecard, with how Bitcoin and gold compare:
| Property | What it means | Gold | Bitcoin |
|---|---|---|---|
| Durability | Doesn’t rot or decay | Excellent | Excellent (digital) |
| Portability | Easy to move/transport | Poor (heavy) | Excellent (data) |
| Divisibility | Splits into small units | Hard | Excellent (1 BTC = 100,000,000 sats) |
| Fungibility | Each unit interchangeable | Good | Good (with caveats) |
| Scarcity | Hard to produce more | Good (mining is costly) | Excellent (fixed 21M cap) |
| Verifiability | Easy to check it’s real | Hard (assay needed) | Excellent (cryptographic) |
| Acceptability | Others will take it | High | Growing |
The smallest unit of Bitcoin is the satoshi (sat): one BTC is 100,000,000 sats. So Bitcoin is more divisible than any physical money — a property that only a digital ledger can offer.
Why this matters for what’s next
Section titled “Why this matters for what’s next”Bitcoin is an attempt to build money that scores excellently on durability, portability, divisibility, scarcity, and verifiability — without a company or government maintaining the ledger. That “without a central keeper” requirement is what turns an easy problem into a famously hard one. We meet that hard problem next.
Check your understanding
Section titled “Check your understanding”- In one sentence, what is money “underneath” all its physical forms?
- How are physical cash and gold a kind of ledger?
- Bitcoin beats gold decisively on two properties in the table — which two, and why?
- Why does “make digital money” really mean “make everyone agree on a ledger”?