In addition to distinguishing costs by product versus G, S, & A classification, other classifications can be used to facilitate managerial decision making. In the next chapter, costs are classified according to the behavior they exhibit when the number of units of product increases or decreases (volume of activity changes). You will learn to distinguish between costs that vary with activity volume changes versus costs that remain fixed with activity volume changes. You will learn not only to recognize cost behavior but also how to use such recognition to evaluate business risk and opportunity.