Waste (also known as rubbish, trash, refuse, garbage, junk, litter, and ort) is unwanted or useless materials. In biology, waste is any of the many unwanted substances or toxins that are expelled from living organisms, metabolic waste; such as urea, feces. Litter is solid waste which has been disposed of improperly.
Waste is directly linked to human development, both technologically and socially. The compositions of different wastes have varied over time and location, with industrial development and innovation being directly linked to waste materials. An example of this includes plastics and nuclear technology. Some components of waste have economical value and can be recycled once correctly recovered.
Waste is sometimes a subjective concept, because items that some people discard may have value to others. It is widely recognized that waste materials are a valuable resource, whilst there is debate as to how this value is best realized. Such concepts are colloquially expressed in western culture by such idioms as "One man's trash is another man's treasure."
There are many waste types defined by modern systems of waste management, notably including:
- Municipal Waste includes household waste, commercial waste, demolition waste
- Hazardous Waste includes Industrial waste
- Bio-medical Waste includes clinical waste
- Special Hazardous waste includes radioactive waste, Explosives waste, E-waste