In economics, the law of diminishing marginal utility is a principle that states that as a person consumes more of a particular good or service, the additional utility (satisfaction) that they derive from each additional unit will eventually decline. For example, if a person eats one slice of pizza, they will experience a certain level of satisfaction. If they eat a second slice, they may experience a slightly lower level of satisfaction, and if they eat a third slice, they may experience even less satisfaction. This is because their hunger is being increasingly satisfied with each additional slice, so the satisfaction they derive from each additional slice decreases.