In economics, rivalry is a characteristic of a good. I.e. merchandise. A good can be placed along a continuum ranging from rivalrous (rival) to non-rival. The same characteristic is sometimes referred to as subtractable or non-subtractable. A rival (subtractable) good is a good whose consumption by one consumer prevents simultaneous consumption by other consumers. Put differently, a good is considered non-rival (non-subtractable) if, for any level of production, the cost of providing it to a marginal (additional) individual is zero. Non-rivalry does not imply that the total production costs are low, but that the marginal production costs are zero. In reality, few goods are completely non-rival as rivalry can emerge at certain levels. For instance, road (or internet) use is non-rival up to a certain capacity, after which congestion means that each additional user decreases speed for others. For that, recent economic theory views rivalry as a continuum, not as a binary category, where many goods are somewhere between the two extremes of completely rival and completely non-rival.