Nano (XNO), formerly RaiBlocks (XRB), is a cryptocurrency. It is a decentralized, open-source, peer-to-peer digital currency based on directed acyclic graph (DAG) architecture, and released under the FreeBSD License. Instead of a single, monolithic blockchain, Nano uses a block-lattice data structure, where every account has its own blockchain. This is a unique implementation of a directed acyclic graph (DAG), where a “block” is just one transaction, and each transaction contains the account's current balance. It's known to be the fastest cryptocurrency in the world.