A Directed Acyclic Graph (DAG) is a type of data structure that consists of nodes connected by edges, where each edge has a direction. In a DAG, there are no cycles, meaning you cannot start at one node and return to it by following the directed edges. This property makes DAGs useful for representing processes with dependencies, such as task scheduling or version control systems like Git. DAGs are commonly used in various fields, including computer science, mathematics, and blockchain technology. In blockchain, for example, DAGs can enhance scalability and transaction speed by allowing multiple transactions to be processed simultaneously without the need for a linear chain.