What is the highest level of a data flow diagram called?

The context diagram represents the highest level of a data flow diagram (DFD). It illustrates the entire system as a single process and shows the interactions between the system and external entities (actors, users, or systems). This overview is essential in understanding system boundaries and external data flows.

BABOK® Reference – Technique: Data Flow Diagrams (Section 10.13):

“The context diagram is the highest level in a data flow diagram, showing the overall system boundaries, external entities, and major information flows.”