Chainlink is a decentralized system that aims to connect smart contracts with real-world data. Since the blockchain is unable to access data outside of its network, the developers of ChainLink offer a solution to this problem. Based on the data obtained from external sources, the system initiates the execution of smart contracts if the predetermined conditions are met. Thanks to cryptography, they ensure the security of data flow, and at the same time facilitate the operation between blockchains. Chainlink's solution: the user requests the data he is looking for from the nodes (currently 21), which provide the requested data or answer. The user then selects the most favorable answer, which would be the least expensive. The requested data is provided by several parties (all competing for the role of oracle), thereby encouraging them to be reliable. Chainlink has countless uses. For example, in the case of securities: this requires data on market exchange rates or interest rates. Payments are made to a real existing bank account, which can be implemented via ChainLink. When paying out insurance, you need data that can be obtained from external sources, for example, whether the aircraft for which the person had insurance arrived on time, i.e. whether the claim for payment is real. GPS data on shipments, the supply chain system, and customs information on the goods to be delivered are usually required when fulfilling commercial contracts. All the necessary data can be added to the smart contract using ChainLink.