What do sequence diagrams primarily convey?

Sequence diagrams primarily convey the order in which behaviors are performed within a system over time. They illustrate how various objects interact with each other through messages exchanged in a sequential manner. Each diagram shows the different components involved in a specific interaction and the sequence of messages that occur, allowing observers to understand how processes flow and how runtime behavior is organized.

This emphasis on the temporal aspect of interactions makes sequence diagrams a vital tool for modeling scenarios where the timing and order of operations are crucial to the system's functionality. By reflecting the sequence of events, these diagrams help in visualizing, validating, and communicating complex interactions in a clear and structured way, thereby enhancing the understanding of the dynamic aspects of the system being modeled.

In contrast, other options like the structure of components or the overall design of the system architecture pertain to other types of diagrams, such as component or architecture diagrams, and do not capture the sequential interaction nature that sequence diagrams emphasize. Similarly, performance metrics fall outside the purview of sequence diagrams, which are more focused on interaction rather than quantitative performance assessment.