Smart Contract
Code that runs on a blockchain, executes deterministically, and cannot be changed once deployed (unless you designed it to be).
A smart contract is a program deployed to a blockchain. Once deployed, its bytecode is immutable, its state is publicly readable, and its execution is governed by consensus rules that nobody can override. That permanence is the feature and the risk: a bug in production is a bug forever, unless you built upgrade machinery in (which itself is a vulnerability surface).
Most production smart-contract systems are not a single contract but a set of them: a proxy for upgradeability, an implementation contract for the logic, often an access-control contract for governance. The pattern is familiar to anyone who has built versioned APIs; the cost of getting it wrong is higher.
Wavect writes smart contracts in Solidity (EVM chains) and Rust (Solana, Near, ICP). For any contract holding non-trivial value we recommend a third-party audit before mainnet deployment. We have shipped audited contracts to production; the audit cost is usually 1 to 2 weeks of the build budget.