A weapon of mass destruction (WMD) is a weapon that can kill and bring significant harm to a large numbers of humans (and other life forms) and/or cause great damage to man-made structures (e.g. buildings), natural structures (e.g. mountains), or the biosphere in general. The scope and application of the term has evolved and been disputed, often signifying more politically than technically. Coined in reference to aerial bombing with chemical explosives, it has come to distinguish large-scale weaponry of other technologies, such as chemical, biological, radiological, or nuclear. This differentiates the term from more technical ones such as chemical, biological, radiological, and nuclear weapons (CBRN).
1. Chemical warfare
Chemical warfare (CW) involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from Nuclear warfare and Biological warfare, which together are the three tenets of (NBC), the military acronym for Nuclear, Biological, and Chemical.

2. Biological warfare
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Biological warfare (BW), also known as germ warfare, is the deliberate use of disease-causing biological agents such as protozoa, fungi, bacteria, protists, or viruses, to kill or incapacitate humans, other animals or plants. Biological weapons (often referred to as bioweapons) are living organisms or replicating entities (virus) that reproduce or replicate within their host victims.

3. Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission (“atomic”) bomb test released the same amount of energy as approximately 20,000 tons of TNT. The first thermonuclear (“hydrogen”) bomb test released the same amount of energy as approximately 10,000,000 tons of TNT
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