A Use relationship indicates that one element requires another to perform some interaction. The Use relationship does not specify how the target supplier is used, other than that the source client uses it in definition or implementation.

You typically use the Use relationship in Use Case diagrams to model how Actors use system functionality (Use Cases).


  • It is more usual (and correct UML) to have an Association between an Actor and a Use Case
  • The Usage relationship, used in Class diagrams, is a different relationship

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