Valuation is the action of assigning value to goods. Value is a subjective and relative concept. Every individual at any given point in time arranges goods on a scale where he differentiates between more and less valuable goods. Those goods that he desires more urgently are located higher than those that he desires less urgently. He only enters into exchange transactions if the goods he can obtain are located higher on his value scale than the ones he surrenders. The location of a good on an individual’s value scale relative to other goods is the value preference that he assigns to it. It is important to point out that, at any time, value preferences are subject to change.