Crypto in plain words, before you touch a wallet · theory, no test network
Six short blocks give you the footing so nothing gets lost later out of ignorance. This is explanations and diagrams only — nothing to click or connect. And on Level 1 you will try everything hands-on, on a safe test network.
A blockchain is a shared ledger of records kept at the same time by thousands of computers around the world. New records are added in "blocks", and each block references the previous one, so you cannot quietly rewrite the past.
There is no head bank in charge here: the network itself accepts records by shared rules, and once confirmed they stay forever.
⚠️ Pitfall. Records are irreversible. Sent to the wrong place — you cannot cancel it or "call the bank".
ETH is the native coin of the Ethereum network: you pay with it for operations on that network. Tokens (for example USDT or LINK) are records inside separate smart contracts on top of the same network, not standalone "network coins".
A stablecoin is a token whose price is deliberately kept close to the dollar (more in block 6).
⚠️ Pitfall. "A token arrived" ≠ "it is worth anything". Scammers send empty bait — we cover this on Level 2.
There are many networks: Ethereum mainnet (real money), fast and cheap L2s, and test networks (for example Sepolia) — on them the coins are fake, they are for practice.
Any record to the network costs gas — a small fee you pay with that network's native coin.
⚠️ Pitfall. The same address exists on all networks — always check which one you are on. On a test network the money is toy money.
A wallet stores not the coins themselves, but the keys to your records on the network. The main one is the seed phrase (12–24 words): the private key and the address are derived from it. Whoever knows the seed controls all the funds.
There is no "support" here to restore access — you are your own bank.
⚠️ Pitfall. The seed — to no one, ever. Do not photograph it or type it on websites. A real service never asks for your seed phrase.
On an exchange the exchange itself owns the keys — handy to start, but "not your keys, not your coins": the exchange can restrict access or run into trouble.
In your own wallet the keys are yours: full control and full responsibility.
⚠️ Pitfall. Everything on an exchange — the risk of trusting it; your own wallet — the risk of losing the seed. Decide deliberately; people often keep a little in both.
How to buy your first crypto on an exchange and safely move it to your own wallet — in the lesson "Exchange and first withdrawal" →
The price is how much money you get for a coin (for example in dollars); it changes all the time. Volatility is the sharp jumps of the price up and down.
Stablecoins are designed precisely to hold their price near the dollar and not jump around.
⚠️ Pitfall. Crypto is not guaranteed income. Beginner's rule: never invest more than you are ready to lose.
Now you have the footing. Next — practice on a safe test network: address, network, gas, a transfer and your first approval.
To practice → Level 1This is theory. Nothing written here needs real money or a wallet.