Notitia
Bridging chains to real-world data.
A blockchain cannot, on its own, know a market price or a sports result. Oracles (like Chainlink) feed such external data to smart contracts in a decentralised, verifiable way.
They are essential to DeFi (asset prices, liquidations) but are a sensitive point: a corrupted feed can be exploited - ‘oracle risk’.
Seven sources report the ETH price. One is manipulated and reports $2,400.
The median ignores the outlier, the average does not: a 2.8% artificial drop is enough to liquidate positions. A pro checks how the oracle aggregates and how many sources would need corrupting.
Test your understanding with a quick interactive quiz.