Directed Acyclic Graph

A Directed Acyclic Graph (DAG) is a finite graph: a set of vertices and directed edges (arcs) where no path can return to its starting vertex (no cycles).

A DAG is a foundational data structure (nodes and one-way connections) crucial for modeling sequential dependencies where order is absolute. The 'directed' property enforces a strict flow (e.g., from Node A to Node B), while 'acyclic' ensures no process can loop back on itself, preventing infinite computation or circular dependencies. This structure enables topological sorting: a linear ordering of vertices consistent with all edge directions. Key applications include data pipeline orchestration (Apache Airflow uses DAGs to define task execution order), blockchain technology (like IOTA's Tangle), and causal inference modeling in statistics and epidemiology.

https://en.wikipedia.org/wiki/Directed_acyclic_graph