A directed acyclic graph (DAG) is a form of Distributed Ledger Technology (DLT). In contrast to a blockchain, which groups transactions into blocks and orders them in a linear fashion, a DAG is a network of individual transactions themselves connected only to other transactions without blocks. While blockchains require block validation, in a DAG, individual transactions provide validation for one another. All network users in a DAG are simultaneously miners and validators, and therefore transaction fees tend to be much lower than those common to blockchain networks.