From Wikipedia.org:
Ripple is a payment system, currency exchange and remittance network by Ripple Labs. It is built upon a distributed, open source internet protocol, consensus ledger and native currency called ripples (XRP). The Ripple network purports to enable "secure, instant and nearly free global financial transactions of any size with no chargebacks". It supports any fiat currency (dollars, yen, etc.), cryptocurrency (bitcoin, litecoin, etc.), commodity or other unit of value (frequent flier miles, mobile minutes, etc.).
Ripple is the most successful Crypto 2.0 protocol. Ripple is an open source, peer-to-peer payments system with 3 – 5 second transaction clear times. Ripple lets you transfer any asset across the network, with automatic currency conversion and fast settlement, while featuring the irreversibility, distributed robustness, and negligible fees that come with cryptocurrency technology.
Link:
http://www.crosscoinventures.com/what-is-ripple/I don't know too much about it, but I think it has something called "gateways" that make it work like a decentralized exchange. It lets you transfer and convert a variety of currencies using the gateways and XRP is the currency used internally within the Ripple ecosystem to facilitate this.
please, explain it to me ..