Sustainability is a characteristic of a process or state that can be maintained at a certain level indefinitely. The term, in its environmental usage, refers to the potential longevity of vital human ecological support systems, such as the planet's climatic system, systems of agriculture, industry, forestry, and fisheries, and human communities in general and the various systems on which they depend.

In recent years an academic and public discourse has led to this use of the word sustainability in reference to how long human ecological systems can be expected to be usefully productive. The implied preference would be for systems to be productive indefinitely, or be 'sustainable."

The term "sustainability" is often used discussion of how to make human economic systems last longer and have less impact on ecological systems, and particularly relates to concern over major global problems such as climate change and oil depletion.

One of the first and most oft-cited definitions of sustainability is the one created by the Brundtland Commission, led by the former Norwegian Prime Minister Gro Harlem Brundtland. The Commission defined sustainable development as development that "meets the needs of the present without compromising the ability of future generations to meet their own needs."

The Brundtland definition thus implicitly argues for the rights of future generations to raw materials and vital ecosystem services to be taken into account in decision making.

Various ways of operationalizing or measuring sustainability have been developed. University of Maryland School of Public Policy professor and former Chief Economist for the World Bank Herman E. Daly (working from theory initially developed by Romanian economist Nicholas Georgescu-Roegen and laid out in his 1971 opus "The Entropy Law and the Economic Process") suggests the following three operational rules defining the condition of ecological (thermodynamic) sustainability:

• Renewable resources such as fish, soil, and groundwater must be used no faster than the rate at which they regenerate.

• Nonrenewable resources such as minerals and fossil fuels must be used no faster than renewable substitutes for them can be put into place.

• Pollution and wastes must be emitted no faster than natural systems can absorb them, recycle them, or render them harmless.

Common principles

Despite differences, a number of common principles are embedded in most charters or action programmes to achieve sustainable development, sustainability or sustainable prosperity. These include

• Dealing transparently and systemically with risk, uncertainty and irreversibility.
• Ensuring appropriate valuation, appreciation and restoration of nature.
• Integration of environmental, social, human and economic goals in policies and activities.
• Equal opportunity and community participation/Sustainable community.
• Conservation of biodiversity and ecological integrity.
• Ensuring inter-generational equity.
• Recognizing the global integration of localities.
• A commitment to best practice.
• No net loss of human capital or natural capital.
• The principle of continuous improvement.
• The need for good governance.

material adapted from Wikipedia