A Goal represents actors’ strategic interests. Tropos distinguishes hard goals from softgoals, the second having no clear-cut definition and/or criteria for deciding whether they are satisfied or not. Softgoals are typically used to model non-functional requirements. For simplicity, Tropos literature usually refers to hard goals when there is no danger of confusion. See Tropos: An Agent-Oriented Software Development Methodology  (p. 207)  for more information about this concept.