A black hole is a place in space where the normal rules of physics break down. It’s called a “hole” because anything that gets too close to it gets sucked in and can’t escape.
Black holes are formed when a very massive star collapses in on itself, or when a lot of matter is squeezed into a very small space. They are so dense and have such strong gravity that not even light can escape from them.
Black holes come in different sizes. The smallest ones are called “stellar” black holes and can be as small as a single atom, but with the mass of a mountain. The largest ones are called “supermassive” black holes and can be millions or billions of times more massive than the sun.
Black holes are really interesting to scientists because they help us understand more about the universe and how it works. But they can also be dangerous, because if you get too close to one, you could get sucked in and lost forever.