Augur is a decentralized oracle and prediction market platform. Users feed real world information into Augur's contracts. Augur ensures the accuracy of this real world information by providing a financial incentive for REP token holders to correct markets they believe have been reported on incorrectly. There are several ways users can participate in Augur: you can trade shares in markets, create prediction markets, or participate in the reporting system to keep the Augur oracle honest.
Augur is built on top of the Ethereum blockchain. Decentralized technology means decentralized contro: no one person can single-handedly change Augur or shut it down. The code is in the hands of the users. Anyone can read the code that runs Augur or copy the code to create a new version that suits their needs.