Hickory Furniture Company had the following costs paid during the month of May: Inventory purchases $40,000 Advertising costs 8,000 Delivery costs 2,000 Hickory sold $32,000 of the inventory and has agreed to pay warranty expenses for its customers. These are expected to be $1,600 and occur evenly over the next four months (i.e., starting in June).

What type of cost is the advertising expense?