All terms
A service that brings outside data, usually prices, onto a blockchain.
Smart contracts cannot see the internet. An oracle publishes external data onchain so contracts can use it, which is essential for lending, derivatives and anything price dependent.
Oracles are a favorite attack surface. Manipulate the price feed for a moment and you can borrow far more than your collateral is worth.
Chainlink aggregates many sources so no single exchange can be manipulated to move the feed.
That the price on chain is the market price. It is whatever the oracle reported, on its own schedule, from its own sources. Almost every large DeFi exploit has an oracle somewhere in the story.
Common questions
Why can a contract not just read a price itself?
What is an oracle attack?
Where this comes up on the site
The guides that actually use this word, rather than a list of everything we have written.
Where to go next
More defi terms
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