Dai is decentralized and backed by collateral. The Maker Protocol, which allows anyone anywhere in the world to generate Dai, aims to facilitate greater security, transparency, and trust.
Ethereum is an innovation network providing its own blockchain with its cryptocurrency (Ether or ETH). This blockchain hosts decentralized applications (DApps) that were first introduced by Ethereum. Another innovation of this platform is the implementation of smart contracts which has changed the perception of the possible use of the blockchain, revealing the potential of the technology to its fullest.
Dent (DENT) is an Ethereum token listed by multiple exchanges. It is the utility token of the Dent telecommunication company. As of now, the Dent apps enable worldwide calls with 85 countries.
Ripple is a global payment protocol aimed to provide fast transactions and cheap payments internationally. The network uses a digital currency known as XRP (sometimes it's referred to as Ripple). Unlike other cryptocurrencies Ripple is not aimed to replace banks, rather this project is created to improve the work of banks (including transactions between different banks) via blockchain solutions.