History of nuclear weapons

Nuclear weapons are really powerful bombs that were created a long time ago. They get their power from splitting or joining together atoms. In the 1940s, scientists developed a way to do this and created the first nuclear weapon. After World War 2, different countries started building nuclear weapons, so that if anyone tried to attack them, they could defend themselves. Nuclear weapons have been used in war twice, and each time it caused a lot of destruction and death. Most countries now have agreed not to use them anymore, but some countries still have them as a part of their military.