DeFi protocols cannot see off-chain prices by themselves. Oracles bridge external data into smart contracts, and their design determines whether a protocol is robust or exploitable.

Three common oracle models:

Push oracles (e.g., Chainlink): nodes periodically post signed prices on-chain; consumers read the latest round.
Pull oracles (e.g., Pyth): prices are stored off-chain and pulled on demand, often with a fee and freshness check.
TWAP oracles: a protocol computes a time-weighted average price from its own pool, making manipulation expensive but slow.

Oracle type	Latency	Manipulation cost	Typical user
Push (Chainlink)	Seconds to minutes	High (node consensus)	Lending markets
Pull (Pyth)	Sub-second	High (signed data)	Perps, options
TWAP	Minutes	Very high (sustained)	AMMs, stablecoins

Oracle failure is a recurring cause of DeFi losses: a stale or manipulated feed can trigger liquidations, mint unbacked stablecoins, or drain lending pools.