This page describes the basic concepts of oracles
Oracles will simply send the current state of the ledgers on the Kusama network to the Moonriver parachain to report all the changes that the ledger underwent in the previous era. When the quorum of the oracle reports is reached, the ledger state on the parachain will be updated and rewards/losses will be applied to the staked funds.
Currently, oracles are run by a few decentralized parties, which increases the security against malicious actions from one party. In the future, we are planning to add a relay chain block parser to ensure that oracle reports are correct.