Our time in this world is very limited, and it constitutes only a miniscule fraction of the whole that makes up world history. This fraction of time can equally be applied to all of those who make up our own generation - but jsut as so, the impact one generation can make on the world can transcend our determined period of time and have repercussions on the world that those after us will inhabit. That is why, sustainability to me is this very awareness of the impact we can have on our home planet, and being conscious of the responsibilities we have as its inhabitants to care for it. It involves taking care of our resources so that they will not run out, and taking care of the planet so that other after us may enjoy it just as we do. It is, in short, a selfless act shared by the billions that inhabit the world, as made up by the likewise countless inidividual efforts to preserve the world as it is, or if possible, to make it even better.