In UML diagrams, you can add relationships to diagram elements to describe how they relate to each other.
Parent topic: Managing relationships between classifiers
Parent topic: Specifying relationships in modeling diagrams
Parent topic: Specifying the flow of control and data in activity diagrams
Parent topic: Specifying the relationships in use case diagrams
Related concepts
Communication paths
Implementation relationships
Manifestation relationships
Realization relationships
Usage relationships
Relationships between model elements
Abstraction relationships
Aggregation relationships
Binding relationships
Composition relationships
Dependency relationships
Directed association relationships
Association relationships
Generalization relationships
Include relationships
Related reference
Relationship types