Black holes are like really big vacuum cleaners in outer space. Imagine the longest vacuum cleaner hose you can think of – way longer than your mom’s vacuum cleaner – with a giant vacuum cleaner at the end. That giant vacuum cleaner sucks up everything nearby, like pieces of dust and stars and planets, and it all gets sucked into the black hole. Nothing can escape from a black hole. That's why it's called a black hole - because even light can't get out!