1. What Is Cryptocurrency?
Module 1 of 12
What Is Cryptocurrency?
Before buying a single coin, it pays to know what you’re actually holding. In plain English: what crypto is, and why “your keys, your coins” is the most important idea in this whole course.
The one-sentence version
Cryptocurrency is digital money that no single company, bank, or government controls — kept honest by a shared record that thousands of computers around the world maintain together. Traditional money relies on a trusted middleman (your bank) to track who owns what. Crypto replaces that middleman with math and a public ledger anyone can check but no one can secretly rewrite.
Four words you’ll actually need
Blockchain
The shared ledger — transactions bundled into “blocks” and chained in order so history can’t be quietly changed.
Coin / Token
The units of value on a blockchain — Bitcoin (BTC), Ether (ETH), and thousands more.
Wallet
Not a store of coins, but the tool that holds your keys — your permission to move them.
Private key
A secret that proves ownership. Whoever holds it controls the coins.
Security rule #1 — starting now
A real wallet or exchange will never ask you to type your seed phrase or private key into a website, form, or chat. Anyone who does is trying to steal from you.
“Not your keys, not your coins”
When you leave crypto on an exchange, the exchange holds the keys — you have an IOU, not the coins. If it freezes withdrawals, gets hacked, or collapses, your money can vanish with it. Self-custody means moving coins to a wallet where you hold the keys: more responsibility, but no company can touch what’s yours. This course teaches you to do it safely.
Key takeaways
- Crypto is decentralized digital money — no central controller.
- A wallet holds your keys, not the coins themselves.
- Holding your own keys = true ownership. That’s the goal.