Chainlink is a decentralized Oracle network that provides an off-chain flow of information for smart contracts running on a variety of blockchains. It aims to make smart contracts a more powerful tool, enabling them to leverage dynamic data input collected from external sources.

Chainlink is a decentralized network of prognosers that addresses interoperability issues for blockchain smart contracts and securely connects them to off-chain data sources, Web apis, and traditional banking payment systems.

On-chain smart contracts themselves do not have access to off-chain data. At present, the external data that triggers the execution of smart contracts (such as Internet of Things data, market data and event data) is basically stored under the chain, and the disconnection between the on-chain and off-chain systems makes the two worlds interoperable.

Oracle, as a blockchain middleware, can help smart contracts connect external off-chain data and realize data interaction between the blockchain world and the real world. It can be applied to many data interaction scenarios, such as stablecoin, lending, financial derivatives, insurance and prediction markets.

Chainlink interacts with on-chain smart contracts by taking on-chain resources (such as Ethereum, Bitcoin and other blockchains) and connecting them to off-chain resources (such as market data, banking payments, retail payments, event data, etc.) through apis. Among them, its on-chain module consists of reputation system, order matching contract and aggregation contract, which is responsible for connecting DApp developers' smart contract and accepting requests for off-chain data. The off-chain module listens for requests and gets data from the node operator.

In the process of the interaction between the on-chain smart contract and the off-chain data, the Token LINK serves as the transaction Token between the data demander and the data provider. LINK tokens are used by payment data providers, Chainlink node operators, payment providers and other online service providers, and smart contract users will incentivize data providers to use LINK tokens. Therefore, the more widely the Chainlink platform is used, the higher the value of the LINK token.

Chainlink uses Schnorr multi-signature to solve the problem of Freeloading (the act of a prophet copying a hash that has previously submitted an answer). Set the maximum number of fault-tolerant nodes to be 2/3 of Chainlink nodes (1/3 of Oracle nodes that are not available and 1/3 of Oracle nodes that are not accurate), and require at least 1/3 of peer prophets to sign to pass verification.

1.Chainlink monitors the validation system's statistics on Oracles by initiating endorsement (certification) of high quality Oracle, and performs post-mortem checks on data submitted to the chain, comparing them to answers obtained directly from reputable sources. Certificate authentication mechanism can restrain witch attack and mirror attack to a certain extent. 2.Chainlink effectively disperses the risk of data distortion due to data source problems by diversifying data sources and prognosers. 3.Chainlink has long introduced trusted execution environments (TEEs) as security for hardware, enabling contract confidentiality and generating reliable randomness.

Chainlink is the first decentralized predictor to go live on the main network, and has unique decentralized data sources, data aggregation, trusted execution environment (private and off-chain computing), reputation system, penalty mechanism, threshold signature, and more.

The model of pledge LINK token becomes the prophet in the prophet system to provide data services for users, score users' behaviors through the credit contract, and reward the good prophet with a certain amount of LINK token reward.

Chainlink has greatly enriched the application of smart contracts in a wide range of industries, including finance, insurance and supply chain. Chainlink provides secure and reliable prognostic services for large corporations such as Google, Oracle, and SWIFT, as well as leading smart contract development teams such as Polkadot & Substrate, Synthetix, Loopring, Aave, OpenLaw, and Conflux. A Chainlink network is a distributed network of Chainlink nodes, all of which directly funnel the use of specific data, apis, and various offline payment functions to smart contracts. With Chainlink, you can call one or more databases within a contract to query the data you need. Chainlink developers can make smart contracts access multiple independent data sources from different nodes, continuously cross-validate, or take the middle of several input values to reduce the probability of errors.

In the allocation of tokens (ICO has sold 350 million in September 2017), 30% of the tokens held by the team (300 million) have not been locked up, which has been sold at a high price before, while the remaining 35% community incentive tokens have not announced a clear pledge reward mechanism.

Chainlink has partnered with a number of star projects and data companies and has over 100 trusted nodes on its platform.