Overview
An oracle is a service that feeds real-world data to smart contracts, enabling them to react to external events and information. Blockchains cannot access the internet on their own, so oracles bridge the gap by delivering data such as asset prices, weather, or sports results in a form smart contracts can use. Reliable oracles are a critical dependency for most DeFi applications.
How It Works
An oracle network collects data from multiple independent sources, aggregates it, and submits updates to the blockchain. Decentralized oracle networks like Chainlink use many node operators and a reputation and staking system so that no single party can manipulate the feed. Smart contracts read these on-chain price feeds to execute liquidations, set interest rates, or settle derivatives.
Why It Matters
If the data a smart contract relies on is wrong or manipulated, the entire protocol can be exploited. Oracle failures have caused some of the largest losses in DeFi history. Choosing trustworthy, tamper-resistant oracles is therefore one of the most important architectural decisions for any protocol that depends on external information, especially for price data that drives financial decisions.
Related Concepts
Oracles support DeFi lending and Derivatives and are frequent targets of Flash Loan manipulation. Decentralized oracle networks contrast with centralized data sources and are often built on Chains with strong staking security.