UML Elements are the building blocks of a model. They are contained in a repository and are depicted in diagrams connected by relationships to create narratives that describe the enterprise, business or software system. Each element has a type that dictates its presentation and the rules that govern how it is connected to other elements. Elements are displayed in a hierarchy in the Project Browser and each element plays a role in defining the system being modeled. They are grouped into structural or behavioral element types, and each type can be used at any stage of the representation of a system. For example, Activities can be used to define the way an organization carries out a business function, or to define the steps in a computer algorithm.
Behavioral Diagram Elements
Behavioral diagrams depict the behavioral features of a system or business process. Elements that can appear on Behavioral diagrams include Activity, Interaction, Lifeline, StateMachine and Use Case.
Structural Diagram Elements
Structural diagrams depict the structural elements composing a system or function. Elements that can appear on Structural diagrams include Class, Component, Interface, Node and Package.