UML diagrams can be categorized into three models:

• Functional Model: Describes the functionality of the system from user’s point of view (Use case diagram).
• Object Model: Describes the structure of system in terms of object , attributes, and operations and associations (Class diagram).
• Dynamic Model: Describes the internal behavior of the system (Sequence diagram, statechart diagram, activity diagram).

Use Case Diagram

Class Diagram

Data Abstraction

Modeling with UML II