Nuclear weapon
There are two types of nuclear weapons: fission weapons (also called atomic bombs or A-Bombs) and fusion weapons (also called hydrogen bombs, H-Bombs, or thermonuclear weapons). They make energy for the nuclear explosion in different ways. Fusion weapons make bigger explosions. Fission weapons use a special isotope of uranium or plutonium. Fusion weapons use a special isotope of hydrogen. Nuclear weapons have been used twice in war, both by the United States in the atomic bombings of Hiroshima and Nagasaki in 1945.