Marginal utility refers to the additional satisfaction or benefit a consumer receives from consuming one more unit of a good or service. It helps explain how people make choices based on the perceived value of each extra unit. For example, the first slice of pizza may provide a lot of enjoyment, but the fifth slice might offer much less satisfaction. As consumption increases, marginal utility typically decreases, a concept known as diminishing marginal utility. This means that while the first few units of a product can be very valuable, each subsequent unit adds less value. Understanding this concept is essential in fields like economics and marketing.