The Ripple Consensus Ledger, or simply RCL, is a pool of ledgers maintained by a netowrk of computers that keep and track the evolution of its ledgers. New transactions are only accepted if a supermajority of network validators agree to include them in the new ledgers, what makes it very secure.
This way, the RCL produces ledgers in a decentralized way, without a central authority, that offers a payment and a trading platform to anyone connected to the internet. Payments in the RCL are fast, (seconds) cheap, final and irreversible.
It is the world's first decentralized exchange.