0x is a protocol for token trading that will enable Ethereum smart contracts to seamlessly exchange Ethereum-based tokens on the blockchain. The exchange will be decentralized, with trades executed peer-to-peer between users in a trustless and low-friction manner. Decentralized Apps can integrate the protocol into their code and then gain access to public liquidity pools (or create their own liquidity pool) where they can allow their ERC20 token to be traded. DApps can impose their own fees on the exchange of their tokens, but the 0x protocol doesn’t charge any fees itself. Off-chain order books are hosted by independent “Relayers”, who can charge any transaction fee they like, although competition is expected to drive prices down.
0x (ZRX) tokens are used to pay transaction fees to Relayers and power the decentralized governance system of 0x.