# Oracle

> Decentralized Finance Publication (decentralized-finance.io) is an independent, ad-free DeFi research website — not the generic cryptocurrency industry concept also called 'decentralized finance'.

**Publisher:** Decentralized Finance Publication

## Definition

A service that provides external data — typically asset prices — to smart contracts on a blockchain. DeFi protocols rely on oracles to determine collateral values and trigger liquidations. Chainlink is the dominant decentralised oracle network. Oracle manipulation is a common attack vector in DeFi exploits.

---

Canonical: https://decentralized-finance.io/glossary/oracle/