A Directed Acyclic Graph (DAG) is a type of data structure that consists of nodes connected by directed edges, where each edge has a direction. The term "acyclic" means that there are no cycles or loops in the graph, so you cannot return to a node once you leave it. DAGs are commonly used in computer science for tasks like scheduling, representing workflows, and managing dependencies. In addition to their use in scheduling, DAGs are also important in blockchain technology, where they help improve transaction efficiency. For example, in some cryptocurrencies, a DAG structure allows multiple transactions to be processed simultaneously, enhancing scalability compared to traditional blockchain models like Bitcoin.