A saleable commodity produced in the process of manufacturing a main product: e.g. manufacturing waste which has. initially perhaps only incidentally, a market value in its own right. By-products may be natural, e.g. sawdust from a carpenter's shed, or may be developed from disposable waste, e.g. the various by-products of the coal industry such as tar, gas, soap, etc.
|Reference: The Penguin Business Dictionary, 3rd edt.|