On the other end, liquidity pools, such as the USDC and DEI pool on Deus, rely on so-called oracles to ensure they are correctly priced at all times and any borrowing is within limits that don’t exceed the total value of those pools. Oracles are blockchain-based tools that provide smart contracts with trusted external information. These are required because blockchains can immutably store data, but can’t verify if the input data are accurate.
www.coindesk.com