A "nuke" refers to a nuclear weapon that releases energy through nuclear reactions, either fission or fusion. These weapons can cause massive destruction and loss of life due to their explosive power and the resulting radiation. The development of nuclear weapons began during World War II, leading to their first use in Hiroshima and Nagasaki in 1945. Nuclear weapons are categorized into two main types: atomic bombs, which rely on fission, and hydrogen bombs, which utilize fusion. The existence of these weapons has led to global efforts for non-proliferation and disarmament, with treaties like the Nuclear Non-Proliferation Treaty (NPT) aimed at preventing their spread.