Smart contract
Self-executing program stored on the blockchain.
Key points
- A smart contract is a program that runs on a blockchain and automatically executes the rules written in code when the conditions are met.
- Once published, it operates without an intermediary and works the same way for everyone, since anyone can read and verify the code.
- It is the technical foundation of applications such as decentralized exchanges, stablecoins, and lending protocols in decentralized finance.
What is a smart contract?
A smart contract is self-executing code published on a blockchain. Its conditions and effects are written directly into program lines: when the requirements are fulfilled, the contract acts on its own, without relying on a trusted party as intermediary. This is what allows agreements to be automated and value to be moved according to fixed, transparent rules.
How it works
The contract is deployed on the network and gets its own address. From then on, users and other contracts can call it by sending transactions. Each call executes the programmed logic and, if applicable, transfers assets or updates the state recorded on the blockchain. Because it runs on the network, each execution consumes a fee proportional to the computational effort involved.
Many contracts need data from the outside world, such as an exchange rate, to decide what to do. This data arrives through oracles, services that bring outside information into the blockchain. The quality of that information directly affects the contract's behavior.
A core characteristic is immutability: once published, the code generally cannot be changed. This provides predictability, but also means that a published error remains until a migration to a new contract takes place.
Why it matters
Smart contracts make it possible to build financial services that operate without a central operator and in an auditable way. For a company integrating on-chain payments, they allow settlement, splitting of amounts, and receiving rules to be programmed directly into the infrastructure, reducing reliance on manual reconciliation.
Risks and limitations
Because the code is public and immutable, a flaw can be exploited by attackers and result in loss of funds with no possibility of reversal. Contracts depend on oracles, which can fail or be manipulated. Audits reduce the risk but do not eliminate it, and the responsibility for interacting with a poorly written contract falls on the user. For this reason, interacting only with well-established, audited contracts, and limiting the amounts exposed in each operation, is a common security practice. </content>