What Is a Cryptocurrency
It isn't money on the internet. It's ownership without an account.
Section 1 ended on one question: who controls the database? A cryptocurrency answers it by taking the database away from any single party — and putting mathematics where the account manager used to be.
The problem
You installed a wallet and moved Bitcoin into it. Open it.
Before you press: decide what you think is in there. Most people expect coins.
The wallet, and the register it points at
Installed, funded, shut. Nothing inside is visible until you open it.
Every participant holds a copy of these rows. The figures are illustrative; where the rows live is the point.
Press Open it and look at what is actually in there.
A wallet is a keyring, not a purse. The coins are rows in a register that many participants keep together — spread across countries and operators — and your private key is what lets you move one of those rows. That is the whole shift: ownership stops being an entry someone maintains for you and becomes something you can prove yourself. It also means the two buttons above behave completely differently, which is worth finding out now rather than later.
The definition
Three things the word hides.
Tap each card for what is actually going on behind it.
Hands on
Pull out a pillar and watch the model fall over.
A cryptocurrency stands on three. Pick one to see what it does — and what is left without it.
None of the three works on its own. Together they produce digital ownership that needs no central account.
The bridge
The four questions, answered.
Section 1 closed with these and left them open. Here is what a cryptocurrency replies — including the uncomfortable one.
Bitcoin is the reference point for all of this, and it is where the detail lives. Which is why a useful next question is not which coin is going up but what problem was this network built to solve — the story the next lesson tells.
Check yourself
Five questions.
Answers come straight from this lesson. Submitting completes it.