Quick Reference Card: Oracles
Smart contracts cannot directly access off-chain data, such as cryptocurrency prices or weather, so they rely on oracles to write that data to the blockchain.
Price feeds are generally updated on-chain when prices move by a specified amount or when a set heartbeat interval elapses.
During sharp price spikes or drops, oracle prices may be slightly out of sync with exchange quotes, so leave a safety margin in your lending positions.
$LINK is the token of the decentralized oracle network Chainlink.