While (thankfully) only a few nuclear bombs have been deployed in war, there have been hundreds of nuclear tests.
In the mid-1900s, the United States conducted hundreds of these tests, mostly in the desert or over oceans. In the U.S., we haven't done one of these exercises since 1991. All nuclear detonations were filmed, but until recently, that footage was classified and held at the Lawrence Livermore National Laboratory. Now, given worldwide instability, these videos have been declassified. The aim? To remind world leaders of the immense destruction nuclear bombs cause and discourage them from blowing us all up.