Definition - What does By-product mean?
A by-product is a secondary, incidental, unintended product or substance produced during an industrial production process or action. Though a by-product is unintended, it has commercial value, contrary to the waste, which has no or a very little value. For example, soybean meal is produced from soybean oil processing or grape seed oil is produced from leftovers of the winemaking process.
Safeopedia explains By-product
By products are found in a wide range of industrial production processes. They may have negative impacts on business and environment. If classified incorrectly, or handled inappropriately, they may be the causes of environmental damages. Such as, if not utilized properly, heat produced in a power plant may warm up the adjacent environment or saw dust produced in a saw mill may pollute the air surrounding it.