The value of something which has to be given up in order to get something else which is desired. (e.g. the environmental cost incurred to obtain economic development). Sustainability can be evaluated by the sum of the various social, economic and natural resources where the degree of use, exchange and trading among resources will vary According to: the values given to each. Trade-off patterns are determined by the different properties of a system, and their importance to different groups. The understanding of social dynamics and resource-use systems and the evaluation of related trade-offs, in terms of equity, productivity, resilience, and environmental stability, are useful to envision alternative development scenarios.