DON (Decentralized OracleNetwork) is a group of independent oracles that provide external data to the blockchain.
Decentralized oracle networks eliminate any single-point-of-failure in the smart-contracts by utilizing multiple data inputs. This enables end-to-end reliability and allows high-value smart contracts in low trust environments to become viable.
How does a DON work?
Every independent node in DON independently retrieves data from an off-chain source and brings it on-chain. The data is then aggregated into a deterministing value of truth for that data point. The value is put on the blockchain in a smart contract (often referred to as a data feed) for us to read from. The value is constantly updated by the DON itself.
If a singular node or source is hacked, depreciated, or deleted, the DON will leverage the decentralized network and carry on.
The most widely-known DON is Chainlink.