The document discusses the accounting principle of lower of cost or net realizable value for inventory valuation. It provides an example of a retailer with leftover iPods that can now only be sold for less than what the retailer paid. Inventory should be recorded at the lower of what was originally paid for the inventory (cost) or the amount it can now be sold for (net realizable value), which may require a write down. The document outlines how to calculate net realizable value and provides a numerical example where coats in inventory will be written down from $50 original cost to the lower $38 net realizable value.