Values are desirable characteristics or qualities of things, ideas, activity patterns, and everything that actually has characteristics. Wiktionary defines value as the quality that renders something desirable or valuable.

 The value is strongly related to a group of people to take advantage of its realization. To address these groups we need to identify them according to the role they are playing in a given use case.

Value is a function of quality and cost. So, on limited resources, not all desired qualities are available in any amount. Priorities need to be specified by the stakeholders.