What does it mean for a good to be rival in consumption?

A good being rival in consumption means that when one individual consumes that good, it diminishes the availability of that good for others. This characteristic signifies that the consumption by one person directly affects the quantity or quality of the good that is left for others to use. For example, if one person eats an apple, that specific apple is no longer available for someone else to eat; thus, the consumption by the first individual reduces the opportunity for others to consume it.

Understanding this concept is crucial in microeconomics because it helps differentiate between types of goods, particularly between private goods, which are rival in consumption, and public goods, which are not. As such, this concept is fundamental in analyzing how goods are allocated in an economy and the implications for resource management and policy-making.