ELI5: Explain Like I'm 5

Marginal factor cost

Marginal factor cost is the cost of using one additional unit of a factor of production (like land, machinery, labor, etc.). For example, if a company needs to use more workers to make more products, the marginal factor cost of adding one more worker is the cost of paying that worker's salary. It is important to businesses because it helps them decide if making more products is worth the cost of the extra labor.