Sustainability is a characteristic of a process or state that can be maintained at a certain level indefinitely (Wikipedia). ‏In a real world, this descriptive definition is not possible to meet and sustainability is not a characteristics of a steady-state processes but rather a characteristics that will change over time for any process.

Applied to human societies, sustainability reaches into all fields of society and our interaction with the planet, which is often depicted by the three main fields of economics, social, and the environment. In each of these fields, we can make many choice that lead away from a sustainable development, or choices that bring us closer to it.