This document discusses different types of costs and their classification. It begins by defining direct and indirect costs, as well as fixed and variable costs. Direct costs include direct materials, direct labor, and direct expenses that can be traced to a specific product. Indirect costs cannot be traced to a specific product. Fixed costs remain constant regardless of production volume, while variable costs change in proportion to production volume. 
It then discusses how costs are classified for different purposes, such as stock valuation, decision-making, and control. For stock valuation, costs are classified as product costs (included in inventory valuation) or period costs (expensed immediately). For decision-making, costs are classified as relevant (those that change with a decision