Nuclear testing refers to the detonation of nuclear weapons to assess their performance and effects. These tests can be conducted underground, underwater, or in the atmosphere. Countries like the United States, Russia, and North Korea have conducted various tests to develop and refine their nuclear arsenals. The practice of nuclear testing has raised significant concerns about environmental damage and human health risks. International treaties, such as the Comprehensive Nuclear-Test-Ban Treaty (CTBT), aim to prohibit all nuclear explosions, promoting global security and reducing the proliferation of nuclear weapons.