What Is a Smart Contract?

A program on a blockchain

A smart contract is code deployed to a blockchain. It stores data and applies programmed rules when users or other contracts call it. The term does not mean the code is intelligent or that it forms a legal contract automatically.

State, calls, and transactions

A contract's state is the data it currently stores, such as balances or permissions. A read call can inspect state without changing it. A transaction requests a state change, must be signed by an account, and consumes network resources that users pay for with a gas fee.

What smart contracts enable

• Exchanging assets according to published rules
• Managing lending, borrowing, or collateral records
• Issuing and transferring tokens
• Coordinating applications whose data and logic can be independently inspected

Important limitations

A contract cannot automatically know facts from the outside world; it needs an oracle or another input. Deployed code may be difficult or impossible to change, depending on its design. Bugs, malicious logic, incorrect permissions, and interactions with other contracts can all create risk.

How to interact carefully

Check the network, destination, requested permissions, and transaction details before signing. A familiar interface does not prove that a contract is safe, and a confirmed blockchain transaction is generally difficult to reverse.

What to remember

• "Smart" describes automated execution, not intelligence or legal enforceability — a smart contract is just code that runs when called.
• A contract can't know facts from outside the blockchain on its own; it needs an oracle or another input to bring in external data.
• Being deployed and publicly visible on-chain doesn't mean a contract has actually been audited for bugs or malicious logic.
• Checking the network, destination, and requested permissions before signing matters because a confirmed transaction is generally difficult to reverse.