Ecovillage members are united by shared ecological, social or spiritual values (see Intentional community). An ecovillage is often composed of people who have chosen an alternative to centralized power, water and sewage systems. Many see the breakdown of traditional forms of community, wasteful consumerist lifestyles, the destruction of natural habitat, urban sprawl, factory farming, and over-reliance on fossil fuels, as trends that must be changed to avert ecological disaster. They see small-scale communities with minimal ecological impact as an alternative. However, such communities often cooperate with peer villages in networks of their own (see Global Ecovillage Network for an example). This model of collective action is similar to that of Ten Thousand Villages, which supports the fair trade of goods worldwide.

In 1991, Robert Gilman set out a definition of an ecovillage that was to become a standard. Gilman defined an ecovillage as a:

human-scale
full-featured settlement
in which human activities are harmlessly integrated into the natural world
in a way that is supportive of healthy human development, and
can be successfully continued into the indefinite future. [1]
Note: In recent years, Gilman has stated that he would also add the criterion that an ecovillage must have multiple centres of initiative.

The principles on which ecovillages rely can be applied to urban and rural settings, as well as to developing and developed countries. Advocates seek infrastructural independence and a sustainable lifestyle (for example, of voluntary simplicity) for inhabitants with a minimum of trade outside the local area, or ecoregion. Rural ecovillages are usually based on organic farming, permaculture and other approaches which promote ecosystem function and biodiversity. Some ecovillages integrate many of the design principles of cohousing, but with a greater ecological focus and a more "organic" process, typical of permaculture design.

An ecovillage usually relies on:

"Green" infrastructural capital;
autonomous building or clustered housing, to minimize ecological footprint;
renewable energy;
permaculture;
cohousing or other forms of supportive community.
The goal of most ecovillages is to be a Sustainable habitat providing for most of its needs on site.
Its organization also usually depends upon some instructional capital or moral codes - a minimal civics sometimes characterized as eco-anarchism:

Local purchasing so as to support the local economy;
local food production and distribution;
moral purchasing to avoid objectionable consumption;
consensus decision-making for governance;
a choice to respect diversity.
The term ecovillage should not be confused with micronation, a strictly legal, not infrastructural, concept.

References
Christian, D. 2003. Creating a Life Together: Practical Tools to Grow Ecovillages and Intentional Communities New Society Publishers. ISBN 0-86571-471-1
Hill, R. and Dunbar, R. 2002. "Social Network Size in Humans." Human Nature, Vol. 14, No. 1, pp. 53-72.[2]
Jackson, H. and Svensson, K. 2002. Ecovillage Living: Restoring the Earth and Her People. Green Books. ISBN 1-903998-16-6