Sustainabillity is an easy concept to grasp on an individual level when it is addressed very simply. What this means is that your consumption is designed to be forever sustainable. That is that the effect on the outside world, and its resources, is done so minorly that you could constantly consume and never run out of the resources you depend on or leave a continually greater destructive effect on the planet. Within this concept we have recycling, reduction of energy uses, composting, and a host of other ideas. What makes this concept great, and the reason it is most likely used out of context by conglomerates fighting over your paycheck, is that this is an easy thing for the individual person to strive for because there are numbers of practical ways they can achieve this.