Too Long; Didn't Read
Chainlink is a project whose aim is to provide all the infrastructure and plumbing for running a network of Oracles that integrate with existing Blockchain networks (Ethereum and others) It's not a Blockchain, but it offers the infrastructure to run heterogeneous networks with oracle nodes that act as intermediaries between Smart Contracts and applications running outside. The value proposition is to offer a mechanism to sell data to apps running in the Chainlink blockchain. Chainlink does not offer or enforce any mechanism for data aggregation. The unit of payments is a LINK token, which is a standard ERC-677 token.