What is Sustainability?
Sustainability is “the ability to be maintained at a certain rate or level; avoidance of the depletion of natural resources in order to maintain an ecological balance.”[1] Simply put it means meeting the needs of the current generation without compromising the ability of future generations to meet their own needs. It encompasses more than just environmental issues.[2] Sustainability includes topics such as social equity, natural resources and economic development spanning over systems economic, environmental, societal and personal. 
Environmental Sustainability: Making sure that the natural resources we use can be replenished while keeping all environmental systems in balance.
Economic Sustainability: Making sure that residents have access to the financial and other resources they require to meet their needs and allow them to access sources of livelihood.
Social Sustainability: Giving residents access to basic resources to keep their families healthy and secure while maintaining universal human rights.
[3] As we continue to grow in social and economic regions, environmental concerns increase. Issues such as pollution, climate change, efficient and affordable energy continue to arise. In order to guarantee resources are available for our future generations, actions must be taken.
[1] https://www.lexico.com/en/definition/sustainability
[2] World Commission on Environment and Development (WCED). Our Common Future. Oxford: Oxford University Press, 1987, p.43
[3] https://www.mcgill.ca/sustainability/files/sustainability/what-is-sustainability.pdf