The term "waste materials" refers to any discarded or unwanted substances that are no longer needed, useful or wanted. These can include solid, liquid or gaseous materials generated from various sources such as households, industries, agriculture and commercial activities among others. Examples of waste materials include paper, plastic, glass, food scraps, construction debris, chemicals, sewage sludge, and other by-products of human activity that are not intended for reuse or recycling. Waste management is an important aspect of environmental protection as it involves the proper disposal, treatment, and reduction of waste materials to minimize their impact on the environment and public health.