What Is a Smart Contract?
A smart contract is a program stored on a blockchain that automatically executes when predefined conditions are met. Written in languages like Solidity (Ethereum) or Rust (Solana), smart contracts enable trustless, permissionless transactions without intermediaries. They power DeFi protocols, NFTs, DAOs, and virtually all blockchain applications beyond simple transfers.
How Smart Contracts Work
A smart contract contains logic: "If X happens, then do Y." For example, a DEX smart contract says "If User A sends Token X, calculate the exchange rate and send them Token Y." Once deployed, the contract runs exactly as written — it cannot be altered, stopped, or censored (in most designs). Anyone can interact with it by sending a transaction with the correct parameters.
Why It Matters for Traders
Smart contracts are the infrastructure of DeFi trading. Every swap, LP position, lending position, and yield farm is a smart contract interaction. Understanding how they work helps traders evaluate protocol risks, identify opportunities in new contract deployments, and avoid vulnerabilities. Smart contract TVL (total value locked) is a key metric for protocol health.