This document provides an overview of marginal costing. It defines marginal costing as a technique that differentiates between fixed and variable costs to determine the effect of changes in volume or output on profit. Marginal cost is defined as the additional cost of producing one more unit. The key features, assumptions, and advantages of marginal costing are outlined, including how it is used for decision making, cost control, and determining profitability. Formulas for calculating break-even point, margin of safety, and other metrics using marginal costing are also presented.