An association is a unidirectional relationship that describes a link between objects.
A use case association can be created in the following diagrams:
You can create an association between:
Associations in a use case diagram are very similar to those in class diagrams. However, it is not possible to specify roles, cardinalities and navigability for associations.
The orientation of the association is defined by the way it is created graphically. An association leading from an actor to a use case is an input association. An association leading from a use case to an actor is an output association.
If the orientation of the association is not displayed, you can modify the association display preferences.
