A Feature is a small, granular function or characteristic expressed in client-valued terms as a satisfaction of a requirement; for example: 'context-sensitive Help', or 'ability to reverse-engineer VB.Net'.
Features are the primary requirements-gathering artifact of the Feature-Driven Design (FDD) methodology. They define the product feature that satisfies what a Requirement element has formalized as a contractual, testable, expected deliverable (for example: requirement - 'every element must provide context-sensitive Help'; feature - 'every element provides context-sensitive Help'). One Feature might realize one or more Requirements, and one Requirement might be realized by more than one Feature.
Features also have relationships with Use Cases. A Use Case defines the interaction a user has with the system in order to satisfy one or more Requirements. The Feature identifies the facility that provides the means for that interaction.
Feature elements are non-UML and are not related to the UML elements of the same name which are either BehavioralFeatures (operations, or methods) or StructuralFeatures (Ports, Parts and attributes).
Feature elements are available from the 'Requirements' page of the Toolbox.
Feature elements can be displayed with or without an identifying 'F' in the top right corner of the element. To toggle the display of this letter, select or deselect the 'Show stereotype icon for requirements' checkbox on the 'Preferences' dialog, 'Objects' page.