Waste, is an unwanted or undesired material or substance. It is also referred to as rubbish, trash, garbage, or junk depending upon the type of material and the regional terminology. In living organisms, waste relates to unwanted substances or toxins that are expelled from them.

Waste management is the human control of the collection, treatment and disposal of different wastes. This is in order to reduce the negative impacts waste has on environment and society.

Waste is directly linked to the human development, both technologically and socially. The composition of different wastes have varied over time and location, with industrial development and innovation being directly linked to waste materials. Examples of this include plastics and nuclear technology. Some components of waste have economical value and can be recycled once correctly recovered.

Biodegradable waste such as food waste or sewage, is broken down naturally by microorganisms either aerobically or anaerobically. If the disposal of biodegradable waste is not controlled it can cause a number of wider problems including contributing to the release of greenhouse gases and can impact upon human health via encouragement of pathogens.

It is difficult to define specifically what a waste is. Items that some people discard have value to others. It is widely recognised that waste materials are a valuable resource, whilst there is debate as to how this value is best realised. Governments need to define what waste is in order that it can be safely and legally managed. Different definitions need to be combined in order to ensure the safe and legal disposal of the waste.

As a nation, Americans generate more waste than any other nation in the world with 4.5 pounds of municipal solid waste (MSW) per person per day, 55 percent of which is contributed as residential garbage. The remaining 45 percent of waste in the U.S.'s ‘waste stream' comes from manufacturing, retailing, and commercial trade in the U.S. economy .

Environmental impact

Waste pollution is considered a serious threat by many and can broadly be defined as any pollution associated with waste and waste management practices. Typical materials that are found in household waste which have specific environmental impacts with them include biodegradable wastes, batteries, aerosols, oils, acids and fluorescent tubes.