Smart Contract
blockchain · scripting
Blockchain-enforced program or script logic that controls how assets or state may change.
A smart contract is code or script evaluated under blockchain rules. It can enforce authorization, value movement, timeouts, and state transitions using data available to the virtual machine.
Account-based contracts commonly keep persistent storage at one address. UTXO contracts usually define spending conditions and carry state into successor outputs. Both models can express complex applications with different concurrency and transaction-construction tradeoffs.
A contract cannot know an off-chain fact unless an oracle or participant supplies it. Frontends, admin keys, upgrade proxies, custodians, and legal enforcement may remain intermediaries even when settlement logic is on-chain.
Code bugs, unclear permissions, oracle manipulation, composability, and recovery design can cause loss. Audits and formal methods reduce uncertainty but do not make a contract risk-free.
Related terms
Opcode
→An encoded instruction interpreted by a virtual machine or transaction script engine.
technical · scripting
P2SH
→A script type where the output is locked to the hash of a redeem script, enabling features like multi-sig.
script · address
Ethereum Virtual Machine (EVM)
→The EVM is the deterministic runtime that executes smart contract bytecode on Ethereum and EVM-compatible networks.
eth · platform · smart contract
Covenant
→A UTXO spending condition that restricts properties of the transaction or outputs created when it is spent.
script · smart-contract · security
Oracle
→A system that supplies on-chain smart contracts with trustworthy off-chain data.
smart-contracts · data