Waste materials refer to outdated (idle) items or those that have been discarded, and are recyclable as reusable resources. They are the items of little value left over in the daily production and life processes. This includes: outdated, scrapped, second-hand, inventory, and materials generated from production and life. Examples include waste metals, waste paper, recycled plastics, and even a significant portion of components from discarded electronic appliances that can be reused and repurposed.

Resource recycling has long been overlooked, as traditional beliefs held that old goods should be discarded and waste should be thrown away. This not only impacts the ecological environment but also these "treasures" possess certain economic value, representing a path to wealth from waste.