The 0x Project is closer to a decentralized cryptocurrency exchange than a centralized one but even then, it has notable differences. 0x addresses the main issues with decentralized exchanges: they are expensive, slow, illiquid, and can’t be operated with each other. To operate an order book on the blockchain, each adjustment or new order goes via the blockchain, meaning that everything is held to block times. This also results in network transaction fees at every interaction.