The hydrogen bomb, or H-bomb, is a nuclear weapon in which light atomic nuclei of hydrogen are joined together in an uncontrolled nuclear fusion reaction to release tremendous amounts of energy. The hydrogen bomb is about a thousand times as powerful as the atomic bomb, or A-bomb, which produces a nuclear fission explosion about a million times more powerful than comparably sized bombs using conventional high explosives such as TNT.

See Fusion, Nuclear Weapon, Thermonuclear.