What Is Oracle?
Also known as: Oracles, Blockchain Oracle, Data Oracle
In short
An oracle is a service or protocol that brings off-chain data, such as prices, weather, sports results, or random numbers, onto the blockchain in a form smart contracts can use. It acts as a bridge between the blockchain and the outside world.
Blockchains work deterministically: when every node executes the same transaction, it must reach the same result. For this reason, smart contracts cannot connect directly to an API on the internet and pull data. Oracles fill this gap; they collect data from external sources, combine multiple sources if needed, and write it on-chain in signed form. For example, a lending protocol uses the ETH price from an oracle to determine the value of collateral and the time of liquidation.
Oracles that depend on a single data source or a single operator create a weak point, no matter how decentralized the rest of the system is; this problem is called the oracle problem. Decentralized oracle networks such as Chainlink collect data from many independent nodes and encourage accurate data through collateral and reputation systems. Projects such as UMA and Tellor use different models based on disputes and voting. Oracles can also offer services such as verifiable randomness and cross-chain messaging.
Oracle manipulation is one of the most common types of attack in DeFi. Protocols that take the price from the instantaneous rate on a single decentralized exchange have suffered large losses because of prices briefly distorted by flash loans. This is why time-weighted average prices (TWAP) and multi-source data feeds are preferred.
Last updated: · This content is for information purposes only and is not investment advice.