To sustain something means to keep it in existence.
Where resources are concerned, sustainability means living so we can meet our needs today in a way that allows people in the future to meet their needs. For example, think about paper and paper products. They are made from the wood of trees. More trees can always be planted, so we don’t need to conserve paper, right? Not necessarily. If people consume so much paper that we use up trees faster than new ones can be planted and grown, then our use of this resource is not sustainable.
Today, we’re not in much danger of running out of trees, but we are running low on some important resources. We’re nowhere near achieving sustainability, but things are changing.
