A smart contract is a program stored on a blockchain that executes automatically when agreed conditions are met. "If the payment arrives, send the ticket", with no middleman who could change their mind.
What this changes
- No trusted third party. The rules are public and the network enforces them.
- Predictability. The same code produces the same result every time.
- Openness. Anyone can inspect what a contract actually does.
Where the limits lie
Code can contain bugs, and a contract that has been deployed often cannot be easily fixed. "Code is law" also means that a bug in the code can be costly and irreversible.
A smart contract does not understand intent. It does exactly what was written, even if the author meant something else.
That is why serious projects go through audits and testing before they reach real users. Automation is powerful, but it does not remove the need for caution. It only moves that caution to the stage where the code is written.