A feature (or user story) describes the ability for a user to perform a specific action: for example, authenticate. The feature is then detailed into different use cases, for example: Log in, Log out, Request a password reset, Reset password, Validate account.

A feature is associated with an Actor (and therefore by extension with all actors who inherit from it): this allows you to visualize the list of all features associated with an actor. 

Similarly, it is possible to visualize all the requirements linked to a feature: Functional or Non-functional requirements, Pages, Forms, Tables.

Each Use case is also linked to a feature.

The details of a feature display the diagram of the Use cases associated with it, the list of these Use Cases as well as the other requirements attached to it: Pages, Forms, Tables, Functional requirements, or Non-functional requirements.

Example of a Use case diagram: