The money
- Cryptocurrency
- Digital money secured by cryptography and recorded on a shared ledger. Full guide →
- Bitcoin (BTC)
- The first cryptocurrency (2009). Digital cash secured by proof of work, capped at 21 million coins. Full guide →
- Ether (ETH)
- The native asset of Ethereum, used to pay for computation on its network. Full guide →
- Altcoin
- Any cryptocurrency other than Bitcoin. The word tells you nothing about quality — "alt" is a category, not a rating.
- Stablecoin
- A token designed to hold a steady value, usually pegged to a currency like the US dollar. The peg is a promise made by the issuer's reserves and processes — check how it's backed before relying on it.
- Token
- An asset created by a smart contract on a platform like Ethereum, rather than built into a protocol. Tokens inherit the platform's ledger security but carry the risk of their own contract.
- Tokenomics
- The economic design of a token: how many exist, how new ones are issued, who holds them, and what they're for. Useful vocabulary for spotting designs that reward early holders at later buyers' expense.
- Blockchain
- A shared, append-only ledger kept by many independent computers, where each block is sealed with the hash of the previous one. Full guide →
- Block
- A sealed batch of transactions added to a blockchain. Each block records the fingerprint (hash) of the block before it — the link that makes it a chain.
- Hash
- A one-way fingerprint of data: easy to compute, impossible to reverse, and completely different for any changed input. Hashes are what seal blocks and prove ownership.
- Consensus
- The rule a network uses for independent computers to agree on one shared history. The two main flavors: proof of work and proof of stake.
- Proof of work (PoW)
- Security by computation: participants compete to solve a hard puzzle; the winner proposes the next block. Bitcoin's model. Costs real energy; resists tampering through cost.
- Proof of stake (PoS)
- Security by collateral: participants lock up value and are selected to validate blocks; dishonesty destroys part of the stake. Ethereum's model since 2022.
- Node
- A computer running the full software for a blockchain, holding a copy of the ledger and enforcing its rules. You don't need one to use crypto; running one is how you verify things yourself.
- Mempool
- The waiting room of unconfirmed transactions. Fees are partly a bid for priority in this queue, which is why network fees rise with demand.
- Confirmation
- Each new block added on top of the one containing your transaction. More confirmations = deeper in the chain = more impractical to reverse.
- Smart contract
- Code that runs on a blockchain and enforces an agreement automatically. Powerful, permanent, and — if buggy — exploitable. The engine behind most DeFi.
- DeFi (decentralized finance)
- Financial applications (lending, trading, and more) built from smart contracts instead of institutions. Real, active, and riskier than holding major assets: you're now exposed to the code, not just the market.
- NFT (non-fungible token)
- A token that represents a unique item on a ledger — art, collectibles, membership. "Unique on a ledger" says nothing about real-world value or provenance.
- Gas
- The fee for running computation on a network like Ethereum, paid in the native asset. "Gas fees" are the network-fee line in our fees guide.
- Fork
- A split in a blockchain's history or rules. Soft forks are compatible updates; hard forks can split a community into two separate chains.
- Wallet
- A tool that holds your keys and lets you send and receive. The coins themselves live on the ledger; the wallet is your access. Full guide →
- Address
- The public part of a key pair — an account number you share to receive. Derived from your public key; safe to share, final if wrong.
- Private key
- The secret that proves ownership and authorizes spending. Whoever holds it controls the coins. Never share it; there is no reset.
- Recovery phrase (seed phrase)
- A human-readable backup of your keys — typically 12 or 24 words. It is your wallet, in backup form. Physical copies, separate locations, never digital. Full guide →
- Custodial wallet
- A wallet where a company holds your keys (exchange accounts, most mobile apps). Convenient, with a customer service line — and you're dependent on the company's security and solvency.
- Self-custody (non-custodial) wallet
- A wallet where you hold the keys. No company can freeze or seize your coins — and no company can help you recover them. Full guide →
- Hardware wallet
- A dedicated device that stores keys offline and signs transactions without exposing the keys to your computer. The standard for protecting meaningful amounts. Full guide
- Hot / cold wallet
- "Hot" = connected to the internet, convenient, more exposed. "Cold" = offline, slower, more secure. The split is about exposure, not the coins.
- Phishing
- Fraud that impersonates a trusted site or person to steal credentials or keys. In crypto, a cloned exchange site is the classic form. Full guide →
- Approval scam
- A trick (often a fake "token unlock" or "airdrop") that gets you to sign a smart contract giving a stranger permission to move your assets. The signature looks harmless; the drain isn't.
- Rug pull
- When a project's developers abandon or betray it — typically by withdrawing the funds behind its token. A reminder that "built on a blockchain" is not a trust claim.
- 51% attack
- When a single party gains enough of a proof-of-work network's mining power to double-spend. Theoretical for Bitcoin at its current scale; a real historical event on smaller networks. A technology risk, not a daily worry for major chains.
- Slashing
- In proof of stake, the destruction of part of a staker's collateral for misbehavior. The penalty that makes staking honest — and a risk if you stake through a faulty provider.
- Drawdown
- A peak-to-trough price decline. Crypto drawdowns of 50%+ are a recurring historical fact for even the major assets — the number your plan must survive.
The technology
The storage
The things that go wrong
Where to go next
Terms are the vocabulary; the guides are the understanding. Start with what cryptocurrency is, then how blockchains work, and — before any purchase — the risks.