Oracle

Smart-contract infrastructure that brings off-chain data on-chain. Most DeFi protocols rely on oracles for price feeds (Chainlink, Pyth, Band). Securing oracle reliability is one of the hardest problems in DeFi — bad oracles enable manipulation attacks (Mango Markets, Nirvana).

Chainlink is the dominant general-purpose oracle network. Pyth specializes in ultra-low-latency price feeds (sourced from major exchanges + market makers).