A quick-reference dictionary of the most important terms in blockchain and Web3. Definitions are kept concise — follow the links in the Learn section for deeper explanations.
Address — A public identifier on a blockchain (like a bank account number). Derived from a public key. Example: 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045.
Airdrop — The distribution of free tokens to a set of wallet addresses, often as a reward for early usage or community participation.
AMM (Automated Market Maker) — A type of DEX that uses a mathematical formula (e.g. x·y = k) instead of an order book to price assets. Uniswap is the canonical example.
ABI (Application Binary Interface) — A JSON description of a smart contract's functions and events. Required to interact with a contract from outside the blockchain.
Block — A batch of transactions grouped together and appended to the blockchain. Each block references the hash of the previous block.
Blockchain — A distributed ledger where data is stored in linked blocks, replicated across many nodes, and secured by cryptography. No single party controls it.
Bridge — A protocol that lets you move tokens or data between two different blockchains (e.g. from Ethereum to Arbitrum).
Bytecode — The low-level machine code that smart contracts are compiled into and that the EVM executes.
Consensus Mechanism — The rules by which nodes in a network agree on the valid state of the blockchain. The two dominant types are Proof of Work (PoW) and Proof of Stake (PoS).
Crypto Wallet — Software (or hardware) that stores your private keys and lets you sign transactions. It does not store your coins — those live on-chain.
DAO (Decentralized Autonomous Organization) — An organization governed by smart contracts and token-holder votes, with no central leadership.