Waste is unwanted or unusable materials.Solid waste means any garbage or refuse; sludge; and other discarded material,including solid, semi-solid resulting from industrial, commercial, mining,and agricultural operations, and from community activities from a waste water treatment plant, water supply treatment plant, or air pollution control facility.

Any material that we discard, that is not liquid or gas, is solid waste

Municipal Solid Waste (MSW):

Solid waste from home or office

Industrial Solid Waste:

Solid waste produced from Mines, Agriculture or Industry.