Marginal cost of production is defined as the increase in total cost as output is increased by one unit. In other words, it is the additional cost incurred by a firm when it produces one more unit of a good or service. This can include the cost of raw materials, labor, and any other variable costs associated with production. By calculating marginal cost, firms can make informed decisions about how much to produce, as they can compare the additional revenue generated by producing an additional unit with the additional cost of producing that unit. This can help firms optimize their production processes and maximize profits.