The Republic Protocol is a second-layer blockchain protocol, that is, a protocol that can be added to a currently existing blockchain that allows for additional functionalities.
When implemented in a decentralized exchange, it turns it into a "dark pool" exchange, with a hidden order book that matches orders without showing their price or volume until execution. It also provides cross-chain asset trading through atomic swaps.
Orders are settled and matched by masternodes called Darknodes. 100Show more [+] 00 REN tokens staked are required to hold a position as a Darknode. The token used the transactions fees to the masternodes are freely defined by each pool adopting the Republic Protocol. Thus, the REN token is bond staked in the blockchain by the Darknodes to ensure its validity instead of a payment method or a validation reward. RenEx is their own dark pool decentralized exchange.