A black hole is believed to be a dying star that collapsed inward from its own weight.
Its pull of gravity becomes so strong that even light can't escape, which is why it looks black!
If you were sucked into a black hole feet first, you'd be stretched out like a piece of spaghetti.
The line between the rest of space and a black hole is called the Event Horizon.
Scientists don't know what happens when you go through a black hole.
Some think any think they might connect two points of the universe together.
Any near us?
Some scientists reckon there's a black hole at the centre of our galaxy.
There's no need to worry, it's still millions of miles away from Earth.