Chainlink is a blockchain interoperability protocol that enables secure, off-chain compute and messaging across permissioned and public systems

Quotes that support claims

Chainlink is a single, generalized, open-source, permissionless, compute-enabled, blockchain-agnostic, API-agnostic, bi-directional, cryptoeconomically-secured connector of on-chain and off-chain systems, built upon a heterogeneous substrate that’s unbounded and without cross-dependencies, ultimately capable of catering to any and all oracle needs.

Chainlink is a decentralized oracle network or blockchain abstraction layer that communicates off-chain data to a blockchain. Its oracles securely enable computations on- and off-chain, supporting what it calls hybrid smart contracts and its cross-chain interoperability protocol.