Chainlink was launched in 2017 to address the inherent limitations of smart contracts, which cannot directly access data outside of their blockchain environment. By utilizing oracles, Chainlink allows smart contracts to pull in external data, such as price feeds, weather data, and other events, facilitating a wide range of on-chain applications. Its decentralized structure ensures reliability and reduces the risk of a single point of failure, as multiple nodes in the network are used to fetch and verify data before it is submitted to the smart contract.