What is cryptocurrency — a beginner's guide
After this module
You'll understand how cryptocurrency actually works — not just the surface, but the mechanics underneath. You'll be able to judge any network or project on your own, instead of just trusting the headline.
Definition
Cryptocurrency = digital money that works without a middleman (a bank) and is recorded on a blockchain (a public digital ledger).
Three defining traits:
- Decentralized — no single server or company is in control
- Limited — the total supply is usually hard-coded (there will never be more than 21M Bitcoin)
- Programmable — rules can be written into it ("smart contracts" — automated programs that execute agreements without a human)
How is it different from bank money?
| Aspect | Bank money | Cryptocurrency |
|---|---|---|
| Custodian | The bank | You yourself (a wallet) |
| Freezing | The bank can | No one can |
| Transfer speed | 1–3 business days | 1–30 seconds |
| Fee | €1–5 (SEPASEPAA European banking system for cheap or free euro transfers between EU banks.) | ~$0.001–0.01 (SolanaSolanaA fast blockchain (under 1s, gas under $0.01). Home to the Kamino, Orca and Meteora ecosystem.Read the lesson →) |
| Hours | 9:00–17:00, weekdays | 24/7/365 |
| Censorship | Possible | Not possible |
| Regulator | Central banks, ECB | A DAO (decentralized autonomous organization), code |
How does it work, technically?
1. The network
Thousands of computers (nodes) around the world run the same software. Each one holds a full copy of the network's history.
2. A transaction
When you want to send 1 SOLSOLSolana's native token. Used to pay gas and as collateral.Read the lesson → SOL to Mary:
1. You sign the transaction with your private key
2. The network receives the transaction
3. Validators (specialized nodes) check:
- Do you actually have enough SOL?
- Is the signature valid?
4. If YES — the transaction is included in a block
5. The block is added to the blockchain
6. Mary sees +1 SOL in her wallet
3. Consensus
The network has a mechanism for agreeing on which transactions are real. There are two main types:
- Proof of Work (PoW) — Bitcoin. Computers solve math puzzles. Slow, expensive, secure.
- Proof of Stake (PoS) — EthereumEthereumA blockchain with smart contracts. We use Aave (lending) and Uniswap (LP) on it.Read the lesson →, SolanaSolanaA fast blockchain (under 1s, gas under $0.01). Home to the Kamino, Orca and Meteora ecosystem.Read the lesson →. Validators (nodes that stake collateral to secure the network) put up their own SOLSOLSolana's native token. Used to pay gas and as collateral.Read the lesson →/ETH as a guarantee. Fast, energy-efficient, secure (as long as most of the network is honest).
Limited supply
Why does this matter?
A central bank for the euro can print as much as it decides it needs. During the 2020–2022 pandemic, billions were printed → that turned into inflation (rising prices) across the eurozone.
No one can print more Bitcoin — the supply is fixed, and new BTC issuance is cut in half roughly every 4 years ("halving", the last one was April 2024):
- 2009: 0 BTC
- 2026: ~20M BTC (already ~95% mined)
- 2140: ~21M BTC (the last one ever)
The smaller the supply, the more value it holds for the same level of demand.
Not every cryptocurrency has a limited supply:
- Bitcoin — 21M (limited) ✅
- Ethereum — ~120M, no hard cap; part of every fee gets burned, which keeps the supply roughly steady
- Solana — no hard cap, but inflation decreases every year
- USDC — no hard cap (1 USDCUSDCA USD stablecoin issued by Circle. Regulated, audited monthly. Our primary stablecoin and loan asset in the Kamino/Aave strategies.Read the lesson → = 1 USD, backed by reserves)
Major cryptocurrencies
| Network | Type | Used for | Fee |
|---|---|---|---|
| Bitcoin | Digital gold | Store of value | ~$0.50–2 |
| Ethereum | Smart contracts | DeFiDeFiDecentralized Finance — financial services without intermediaries, operating through smart contracts.Read the lesson →, NFTsNFTNon-Fungible Token — a unique token. Uniswap V3 LP positions are NFTs. | ~$0.01–0.30 |
| Solana | Fast network | DeFiDeFiDecentralized Finance — financial services without intermediaries, operating through smart contracts.Read the lesson →, gaming | ~$0.001–0.01 |
| Arbitrum | EthereumEthereumA blockchain with smart contracts. We use Aave (lending) and Uniswap (LP) on it.Read the lesson → L2 | Cheaper access to EthereumEthereumA blockchain with smart contracts. We use Aave (lending) and Uniswap (LP) on it.Read the lesson → | <$0.01–0.05 |
Fees move with network load — the table shows quiet-period ranges; during congestion they can spike several times over. Before a larger EthereumEthereumA blockchain with smart contracts. We use Aave (lending) and Uniswap (LP) on it.Read the lesson → transaction, it's worth a quick look at etherscan.io/gastracker.
What you're actually managing
Every property of crypto comes with a trade-off you'll learn to handle. Here they are — not as warnings, but as a list of things this course will teach you to manage yourself:
- Price swings (30–50% in a week) → this is the risk premium for the upside; later on (module 5) you'll learn to hedge with options and manage the swings
- Losing your seed phrase → write your recovery phrase down offline and store it safely (the full method is in module 2), and then no one can take it from you
- Scam projects (meme tokens, rug pulls) → stick to vetted, audited protocols; you'll build the pattern-recognition skill in module 2
- Regulation → follow the rules and pay your taxes (in Lithuania — 15% GPMGPMGPM — Lithuanian personal income tax; 15% on realised crypto gains., the personal income tax, on realized gains); covered in module 2
- Smart contract bugs → choose only audited protocols with a long track record (AaveAaveEthereum lending protocol (v3). In our strategy: ETH collateral to a USDC loan., KaminoKaminoSolana lending protocol. In our strategy: SOL collateral to a USDC loan.), not new, unproven ones
Every risk has a solution. You don't need to fear it — you learn to manage it. Practical starting point: begin with an amount small enough that you can watch it calmly while you learn.
Once you understand this mechanic, you can judge any crypto pitch yourself: you see a big promise → you ask "what risk am I being paid to take here?" — and you know exactly where to look for the answer.
Summary
- Cryptocurrency = digital money without a bank
- Runs on a blockchain (a public ledger)
- YOU are your own bank (you hold the keys)
- Limited, programmable, often global
- Bitcoin = the first and the largest
- EthereumEthereumA blockchain with smart contracts. We use Aave (lending) and Uniswap (LP) on it.Read the lesson →/SolanaSolanaA fast blockchain (under 1s, gas under $0.01). Home to the Kamino, Orca and Meteora ecosystem.Read the lesson → = platforms for programmable money (DeFiDeFiDecentralized Finance — financial services without intermediaries, operating through smart contracts.Read the lesson →)
Theory says blockchain is a public ledger anyone can see. Check it yourself — takes about 5 minutes, nothing to buy.
This is learning, not investing — use only small amounts you treat as tuition.
You just read a real transaction on the blockchain and compared its fee to a bank transfer — now you can talk about crypto from experience, not hearsay.