A WORD, AN EXPLANATION

Crypto & Blockchain Lexicon

Clear definitions and concrete examples. Search in English or French, with or without accents.

A

Address

An identifier used on a network to receive assets or interact with an account or contract. An address alone does not identify the network or token.

Example: The same 0x-format address can be used on multiple Ethereum-compatible networks.

Airdrop

Distribution of tokens under a project’s criteria. An announcement can be fraudulent and a signature request needs checking.

Example: Hypothetical example: a project allocates tokens to earlier users.

Altcoin

A common term for a cryptocurrency other than bitcoin.

Example: ETH is Ethereum’s native asset; SOL is Solana’s.

AMM (Automated Market Maker)

Protocol enabling automatic token exchange through liquidity pools and mathematical formulas.

Example: Uniswap, SushiSwap, PancakeSwap

Arbitrage

Seeking a price difference between markets; fees, delays and price changes can erase the result.

Example: Hypothetical example: buying at 100 and selling at 101 does not earn 1 net if fees total 2.

B

Bear Market

A period with a broadly downward trend. It can include rallies.

Example: A market can fall over several months despite rising in some weeks.

Bitcoin

A peer-to-peer payment network using a blockchain. Its native asset, bitcoin (BTC), is transferred through signed transactions.

Example: A BTC transaction is verified by Bitcoin nodes.

Blockchain

A ledger of transactions organised into cryptographically linked blocks. Resistance to changes depends on consensus rules and network security.

Example: Bitcoin and Ethereum each use their own blockchain.

Bridge

A mechanism linking networks to transmit messages or represent assets. It adds its own risks.

Example: A rollup withdrawal to Ethereum follows its bridge rules.

Bull Market

A period with a broadly upward trend. It can include corrections.

Example: A past rise does not guarantee the trend will continue.

Burn

Removal of units from usable supply under protocol or contract rules.

Example: Ethereum’s base transaction fee is burned; the tip is not.

C

Cold Storage

Keeping signing keys away from a connected device. Assets remain recorded on the blockchain.

Example: A hardware device can isolate the key, but a harmful signature remains dangerous.

D

DAO (Decentralized Autonomous Organization)

An organization coordinating some decisions with blockchain tools; voting rights and execution vary.

Example: A treasury can be managed by a multisignature account following a vote.

DApp (Decentralized Application)

An application with some logic using a decentralized network. Its interface can remain centralized.

Example: A website prepares a swap executed by a smart contract.

DeFi (Decentralized Finance)

Financial services using smart contracts. Dependencies on code, oracles and operators remain.

Example: A contract manages collateral and lending rules.

Dust

A very small asset amount. Bitcoin’s dust threshold depends on output type and fee policies, among other factors.

Example: Spending a small balance can cost more than its value.

E

Ethereum

A blockchain network that can execute smart contracts. Its native asset is ether (ETH).

Example: An application can use a smart contract deployed on Ethereum.

F

Fork

A temporary history divergence or a change in protocol rules. A rule change does not always create two lasting networks.

Example: A hard fork can make some old rules incompatible with new ones.

G

Gas

A unit of execution resources, notably on Ethereum. Gas quantity and gas price are different.

Example: Hypothetical example: 21,000 units at 10 gwei cost 0.00021 ETH.

H

Halving

A protocol-scheduled halving of the block subsidy. Bitcoin transaction fees are not halved.

Example: Bitcoin schedules a halving every 210,000 blocks, roughly four years.

Hot Wallet

A wallet with signing credentials used on a connected device. Security also depends on the device and permissions.

Example: A wallet app on a connected phone.

I

ICO (Initial Coin Offering)

Fundraising through the sale of new crypto tokens.

Example: Ethereum's ICO in 2014

K

KYC (Know Your Customer)

Process of verifying users' identity on crypto platforms.

Example: Providing your passport to register on an exchange

L

Layer 2

A network that executes transactions while relying on a base blockchain for part of its security. Guarantees vary by design.

Example: Arbitrum and Optimism rollups on Ethereum.

Leverage

Trading with borrowed funds to amplify gains (and losses).

Example: Trading with 10x leverage

Liquidity Pool

Reserve of tokens locked in a smart contract to facilitate trading.

Example: ETH/USDT pool on Uniswap

M

Market Capitalization

Price multiplied by estimated circulating supply. It is not the amount invested or available for withdrawals.

Example: Hypothetical example: 1 million tokens priced at 2 euros give a 2 million euro market cap.

Mining

Searching for proof of work to propose a block. Nodes independently validate it.

Example: A Bitcoin miner tests many hashes using specialized hardware.

N

NFT (Non-Fungible Token)

A token with a distinct identifier. Rights over a linked image or item do not automatically transfer with the token.

Example: A numbered ticket represented by a token, subject to the organizer’s terms.

Node

Computer participating in the blockchain network by validating and relaying transactions.

Example: Running a Bitcoin node

O

Oracle

Service providing external data to smart contracts.

Example: Chainlink providing crypto prices

P

Passkey

A cryptographic authentication method. Its use and account recovery depend on the service or wallet.

Example: A passkey can unlock a service without being the private key controlling the assets.

PoS (Proof of Stake)

Consensus mechanism where validators stake tokens to secure the network.

Example: Ethereum uses PoS

PoW (Proof of Work)

A mechanism requiring computational proof that is costly to produce and easy to verify.

Example: Bitcoin searches for a block-header hash below a target.

Private Key

Secret code allowing to sign transactions and access funds.

Example: A string of 64 hexadecimal characters

Public key

A cryptographic value derived from a private key, used to verify signatures. An address may be derived from a public key; they are distinct objects.

Example: On Ethereum, an externally owned account address is derived from a hash of its public key.

R

Recovery phrase

A sequence of words that restores keys in some wallets. Keep it secret; it is not a receiving address.

Example: A wallet can offer a 12- or 24-word backup.

ROI (Return on Investment)

Measure of profit or loss generated by an investment.

Example: A 200% ROI means tripling your investment

S

Slippage

The difference between an expected price or amount and the executed result. Tolerance sets a limit, not a guaranteed gain.

Example: A swap can revert if its minimum received amount cannot be met.

Smart Contract

A program on a blockchain that executes when called. It does not run simply because time passes.

Example: A transaction calls a contract’s swap function.

Stablecoin

A token targeting a reference asset’s value. Its peg can fail and redemption depends on its mechanism.

Example: A dollar-targeting stablecoin can change in euro value even without losing its peg.

Staking

Participation in PoS network security with assets at stake. Rewards, penalties and delays vary.

Example: Solo validation and a staking service involve different risks.

W

Wallet

A tool for viewing accounts and preparing or signing actions. Key custody and recovery depend on its design.

Example: A wallet displays a balance recorded on a blockchain.

Y

Yield Farming

Seeking rewards through different protocols. Fees and losses can outweigh those rewards.

Example: A token reward can lose value before it is withdrawn.