What type of diagram helps visualize interactions in a system?

A sequence diagram is designed specifically to illustrate how objects interact in a particular sequence, highlighting the order of messages exchanged between them over time. This type of diagram is part of the Unified Modeling Language (UML) and is particularly useful in understanding dynamic behavior within a system.

The primary focus of a sequence diagram is on the time sequence of these interactions. It delineates the various components involved (often represented as vertical lines) and shows how and when they communicate with one another through horizontal arrows that represent messages, such as method calls or events. This enables stakeholders to grasp how specific functionalities are executed in a system, which is critical for analyzing requirements and understanding the user interactions with the system effectively.

In contrast, other diagram types such as flowcharts or organizational charts serve different purposes, such as depicting processes or hierarchical structures, rather than focusing specifically on the timing and sequence of interactions. An entity-relationship diagram, on the other hand, focuses on the relationships between data entities rather than the interactions between objects over time. Thus, the sequence diagram stands out for its unique ability to provide insight into the interactions within a system.