What is the Unified Modeling Language (UML) technique that visually represents the interaction between users and an information system?

The Unified Modeling Language (UML) technique that visually represents the interaction between users and an information system is a Use Case Diagram. This type of diagram focuses on capturing the functional requirements of a system by illustrating the various ways users (or "actors") will interact with the system to achieve specific goals.

Use Case Diagrams depict the system's boundaries and show the different use cases or scenarios that the users can perform. Each use case represents a distinct function or set of actions executed by the system in response to an actor's interaction. This provides a high-level view of user interactions without delving into the details of how these interactions are implemented in the system.

In contrast, other diagrams such as flowcharts, data flow diagrams, and class diagrams serve different purposes. Flowcharts primarily represent processes and workflows, data flow diagrams illustrate data movement within a system, and class diagrams outline the structure of a system by showcasing classes and relationships among them. While useful in their contexts, these diagrams do not specifically focus on the interactions between users and the system in the manner that use case diagrams do.