Okay kiddo, so you know how we play with blocks and Legos, right? Well, countries like the United States and Russia also have something like blocks that are much much bigger called nuclear bombs.
Now, these bombs are very powerful and can cause a lot of destruction if they are ever used. That's why scientists and governments want to make sure they know how powerful they are and how they might affect things around them if they go off.
So, they do something called high explosive nuclear effects testing. This means they set off a small nuclear bomb in a safe and controlled area to see how things react around it. They might test things like buildings, bridges, and even animals to see how they are affected.
But don't worry, they always make sure to keep everyone safe by doing these tests in a place where no one else is around. And they use the information they gain from these tests to help make sure we're all safe and understand how to prevent nuclear disasters.