0x is an infrastructure protocol that allows users to easily trade ERC20 tokens and other assets on the Ethereum blockchain without relying on centralized intermediaries like traditional cryptocurrency exchanges. 0x achieves this decentralized exchange functionality using a collection of open-source, publicly auditable smart contracts that work together to produce a flexible, low-friction trading protocol that developers can easily weave into their products. The protocol is powered by an ERC20 utility token known as ZRX. Nodes that (also known as relayers) host an off-chain order book and offer user-facing applications that present this information and allow users to make, fill and cancel transactions are paid in ZRX tokens (as trading fees).