Which UML diagram represents interactions over time?

The sequence diagram is specifically designed to illustrate how interactions occur over time between different components or objects in a system. It displays the order of message exchanges and the timelines of those interactions, allowing you to visualize how the objects in a system collaborate through messages.

In a sequence diagram, the vertical axis represents time, with messages flowing from one object to another along the horizontal axis. This approach highlights the sequence and timing of events, making it ideal for understanding dynamic behavior in a system. The diagram therefore effectively captures temporal aspects of interactions, such as when actions start and finish, which is critical in many scenarios, particularly in software design and understanding complex systems.

Other diagram types serve different purposes. For example, class diagrams show the static structure of a system by depicting classes and their relationships, while communication diagrams also present interactions but focus on the structural organization of the objects involved rather than the timing of the interactions. Deployment diagrams showcase how software components are physically placed on hardware, detailing the configuration of the system rather than the dynamics of its operation.