Directed Acyclic Graph
A Directed Acyclic Graph (DAG) is a form of Distributed Ledger Technology (DLT) and an alternative to a blockchain. Instead of blocks, DAGs store transactions as vertices on top of one another, allowing for multiple transactions to be referenced simultaneously. These vertices are connected so that each edge only goes in one direction so that no cyclic connections can be made. Individual transactions can provide validation for each other.
Since transactions are constantly being validated by other transactions, DAGs are best suited for networks with high volumes of transactions. However, this can lead to security concerns when there are insufficient transactions on the network.