Chainlink is a middleware framework designed to connect blockchain smart contracts with real-world data through APIs, enhancing the Ethereum oracle ecosystem and facilitating off-chain data usage. Chainlink provides a standardized data middleware layer, enabling smart contracts to interact with any external API, supporting a wide range of operations in the DeFi space. At its core, Chainlink employs adapters, which allow developers to create standardized interfaces for data requests and node operators to supply data accordingly, including HTTP GET and POST among others. Additionally, external adapters offer flexibility by allowing developers to handle data in any programming language and interface specifications off-chain, thereby reducing gas costs while maintaining functionality. Chainlink's infrastructure empowers developers to build more sophisticated smart contract applications by using a mix of basic and external adapters to connect to diverse data sources, ultimately aiming to bridge the gap between on-chain contracts and off-chain data in a reliable and cost-effective manner.