Crypto
Oracle (blockchain)
A system that brings real-world information, such as a price or an election result, onto a blockchain so smart contracts can act on it.
Polymarket's markets settle on-chain, so something has to tell the contract who won. That is the oracle's job. Polymarket uses UMA's optimistic oracle, where a proposed answer stands unless challenged within a window.
Oracles are a point of failure and of controversy: a wrong or manipulated answer can misresolve a market. The bond-and-dispute design makes attacks expensive but not impossible.
Regulated exchanges such as Kalshi do not need an oracle; they resolve markets by their own rules.
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Frequently asked questions
- What does "Oracle (blockchain)" mean?
- A system that brings real-world information, such as a price or an election result, onto a blockchain so smart contracts can act on it.
- Why does oracle (blockchain) matter for prediction markets?
- Regulated exchanges such as Kalshi do not need an oracle; they resolve markets by their own rules.