What is Sustainability?   
The 21st Century accepted model of Sustainable Development is (in NO order of priority):

A: Social Inclusion:
All people regardless of gender, race, age or class, are entitled to Human Rights (shelter,
food, safety, independence, education and a Democratic vote.)

B: Stable Economy:
Be it local, national or Global – all businesses/Co-Operatives should be stable with emphasis on the immediate communities that they locally occupy, as well as the Global implications.

C: Benign Ecological Activity:
All work, play and other processes undertaken by humanity can be achieved with no real impact upon the natural Earth. All resources are used appropriately, sharing and sparingly.