The Class diagram is the main static analysis diagram for a system. It specifies the class structure of the system with relationships between classes and inheritance structures.

In a problem-driven approach to OO analysis, you develop a class diagram through information garnered from the Use Cases, the Sequence diagrams, and the Collaboration diagrams. The objects found during problem-driven analysis lead the user to model the classes they instantiate. The links among objects provide a map to modeling the relationships among their classes. Collaboration diagrams provide the most useful information, in that they show interactions among objects to solve a particular problem.