Sustainability is an economic, social and an ecological concept.

In economics, sustainable growth consists of increases in real incomes (i.e. inflation-adjusted) or output that could be sustained for long periods of time.

The modern concept of ecological sustainability goes back to the post-World War II period, when a utopian view of technology-driven economic growth gave way to a perception that the quality of the environment was linked closely to economic development. Interest grew sharply during the environmental movements of the 1960?s, when popular books such as Silent Spring by Rachel Carson (1962) and The Population Bomb by Paul Ehrlich (1968) raised public awareness.

There are two related categories of thought on ecological sustainability. In 1968 the Club of Rome, a group of European economists and scientists, was formed. In 1972 they published Limits to Growth. Although discredited by many, it predicted dire consequences because the earth was using up its resources, and it advocated as one solution the abandonment of economic development. Groups sympathetic to the general premise that the world was growing too quickly and/or using up its resources formed, including the Worldwatch Institute in 1975. In a different category, other groups formed to focus less on population growth control and slowing economic development, and more on establishing environmental standards and enforcement.

The original term was "sustainable development," a term adopted by the Agenda 21 program of the United Nations. Some people now object to the term "sustainable development" as an umbrella term since it implies continued development, and insist that it should be reserved only for development activities. Sustainability is, then, used as an umbrella term for all of human activity.

Sustainability is ensuring the next generation is able to live as well as this one or better.

Another definition might be like this one: Sustainability is a means of configuring civilization and human activity so that society and its members are able to meet their needs and express their greatest potential in the present while preserving biodiversity and natural ecosystems, and planning and acting for the ability to maintain these ideals indefinitely.

Or, in simpler terms, sustainability is providing for the best for people and the environment both now and in the indefinite future.

This is very much like the "seventh generation" philosophy of the Native American Iroquois Confederacy, mandating that chiefs always consider the effects of their actions on their descendants through the seventh generation in the future.

Many people have pointed to various practices and philosophies in the world today as being inimical to [against] sustainability. For instance, critics of American society state that the philosophy of infinite economic growth and infinite growth in consumption are completely unsustainable and will cause great harm to human civilization in the future.

One of the critically important issues in sustainability is that of human overpopulation. A number of studies have suggested that the current population of the Earth, already over six billion, is too many people for our planet to support sustainably. A number of organizations are working to try to reduce population growth, but some fear that it's already too late. Critics of such efforts, on the other hand, fear that efforts to reduce population growth may lead to human rights violations such involuntary sterilization and the abandoning of infants to die. Some human rights watchers report that this is already taking place in China as a result of its one child per family policy.

Sustainability affects every level of organization, from the local neighborhood to the entire globe.

See also sustainable development, sustainable design, renewable energy.