This definition, from the Cohousing Association of the United States, says it well:
Cohousing is a form of intentional neighborhood in which residents actively participate in the design and operation of their own community. In cohousing, residents know their neighbors well and enjoy a strong sense of community that is typically absent in contemporary cities and suburbs.
Cohousing communities consist of private, fully equipped dwellings and extensive common amenities including a common house and recreation areas. Most communities forge a strong partnership with a professional development team. Together they create a custom-built, resident-managed, close-knit neighborhood that offers a healthy balance of privacy and community.
You can learn more about cohousing from their site — http://www.cohousing.org — if this concept is new to you. They offer many different models for organizing a community.
Here at the Pinnacle Project, we intend to build a community from a group of old and new friends on the property of the Loch Lyme Lodge in Lyme NH. Please read our materials on this site to learn more, and please contact us if you have an interest in meeting with us.