A by product is a secondary unit produced in a joint production process that has little value in relation to the main product being produced. In other words, it’s a unit that is created inadvertently during the process of manufacturing another product. By-products occur in almost all industries not just manufacturing. Take farming for example. Dairy farmers breed and raise cows to produce milk in order to sell it to grocery stores, restaurants, and distributors. What is a by-product of cattle? Manure. The farmer isn’t trying to start a manure farm. He or she is interested in producing milk, but the manure is created during the process. The manure doesn’t have the same value that the milk does, but it does still have value. Farmers typically sell manure to landscapers or fertilizer companies that process the waste into fertilizer for farms, greenhouses, and home gardens. There are numerous other processes that create useful by products. Take the logging industry for instance. The main products of this industry are whole logs, but every tree has branches and smaller sections that can’t be used as full logs. These sections are typically ground up in a wood chipper to make wood chips. These are then sold to professional landscapers and home garden enthusiasts.