Sustainability, or the ability to be sustained, essentially means something can be continued or prolonged for an extended period of time (Apple Inc. 2015). A common use of this word comes from the world of commerce: if a business is sustainable, it has the potential to be profitable over the long term. A currently popular, but narrow, view of sustainability considers something to be sustainable if it minimizes damage to the natural environment. However, minimizing damage is a low bar to hurdle: simply minimizing damage does not necessarily mean that something creates more good than bad with respect to the environment. Instead, the test of environmental sustainability is usually applied in relative terms: will this something have the same function but produce less environmental damage than the something that society uses now? The “something” can be a measure (plan, policy, or course of action), a system (procedure, process, or set of related processes), or an entity (product, device, or infrastructure). One can imagine many measures, systems, or entities that have the ability to have prolonged financial profit, or prolonged environmental benefit (in absolute or relative terms). However, a broader definition of sustainability considers  environmental, social, and economic sustainability to be essential. Barbier depicted sustainability as the common centre of a Venn diagram consisting of three overlapping circles, representing environmental sustainability, social sustainability, and economic sustainability.

可持续性，或可持续性的能力，本质上意味着某种东西可以持续或延长一段时间（苹果公司，2015年）。这个词的一个常见用法来自商业世界：如果一个企业是可持续的，它就有可能长期盈利。目前流行但狭隘的可持续发展观认为，如果能将对自然环境的破坏降到最低，那么它就是可持续的。然而，将损害最小化是一个很低的障碍：简单地将损害最小化并不一定意味着某种东西对环境造成的好处多于坏处。相反，环境可持续性的测试通常是用相对的术语来进行的：这种东西是否会有同样的功能，但比社会现在使用的东西产生的环境破坏要少？“某物”可以是度量（计划、策略或行动过程）、系统（过程、过程或一组相关过程）或实体（产品、设备或基础设施）。人们可以想象许多措施、制度或实体，它们有能力获得长期的财政利润或长期的环境效益（以绝对或相对的方式）。然而，更广泛的可持续性定义认为环境、社会和经济可持续性至关重要。巴比尔把可持续性描述为维恩图的共同中心，维恩图由三个重叠的圆圈组成，代表环境可持续性、社会可持续性和经济可持续性。