Cost objects are items for which management wants to track costs, direct costs are costs that can be traced to specific cost objects, and indirect costs are costs that cannot be directly traced to cost objects. Fixed costs remain the same regardless of activity levels while variable costs change in relation to changes in activity. Direct materials, direct labor, and manufacturing overhead are costs of production that are included in inventory and eventually become part of the cost of goods sold, while period, selling, and administrative costs are operating expenses.