The System Context Diagram is a visual representation of the interactions between a system and its environment. It provides an overview of the system's external entities and their relationships to the system, as well as the system's boundaries. The diagram can be used to identify the system's inputs and outputs,
From Wikipedia
A system context diagram in engineering is a diagram that defines the boundary between the system, or part of a system, and its environment, showing the entities that interact with it. This diagram is a high level view of a system. It is similar to a block diagram.