Smart Contract

A smart contract is self-executing, immutable code on a blockchain: it automates the 'if/when X, then Y' logic of an agreement without needing a third-party intermediary.

Smart contracts are digital agreements: code written (often in Solidity) and deployed to a decentralized network, like Ethereum, that automatically executes a transaction when predefined conditions are met. Conceptualized by Nick Szabo in 1994, this technology removes the need for costly middlemen (lawyers, banks) by making the contract terms self-enforcing and tamper-proof. Think of it as a vending machine for digital assets: insert 1 ETH (condition met), and the contract automatically dispenses the NFT (action taken). This core function underpins all decentralized finance (DeFi) and non-fungible token (NFT) systems, guaranteeing security and transparency across all parties.

https://www.investopedia.com/terms/s/smart-contracts.asp