A by-product is a secondary product derived from a manufacturing process or chemical reaction. It is not the primary product or service being produced. In the context of production, a by-product can be defined as the 'output from a joint production process that is minor in quantity and/or net realizable value (NVR) when compared to the main products'. Because they are deemed to have no influence on reported financial results, by-products do not receive allocations of joint costs. By-products also by convention are not inventoried, but the NRV from by-products is typically recognized as 'other income' or as a reduction of joint production processing costs when the by-product is produced. A by-product can be useful and marketable or it can be considered waste.