Orca Crypto
DeFi term

Oracle

A service that brings outside data, usually prices, onto a blockchain.

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Updated 2026-08-303 min readDefinition
Definition

A service that brings outside data, usually prices, onto a blockchain.

Smart contracts cannot see the internet. An oracle publishes external data onchain so contracts can use it, which is essential for lending, derivatives and anything price dependent.

Oracles are a favorite attack surface. Manipulate the price feed for a moment and you can borrow far more than your collateral is worth.

In practice

Chainlink aggregates many sources so no single exchange can be manipulated to move the feed.

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