Nib asked, and Nib — askNib's tutor — drew the answer live at a whiteboard. This is the spoken transcript; enable JavaScript to watch it drawn.
What is a black hole, and what would happen if you fell in? (for a curious adult who has not studied physics). Cover, in this order: What is a black hole?; How can gravity be strong enough to trap light?; How does a black hole form?; What is the event horizon?; What happens if you fall into a black hole?; If nothing escapes, how do we see black holes?; Do black holes really suck everything in?; Can a black hole die? — page 7: Do they suck everything in?
Picture a black hole as a drain that sucks in everything. But gravity depends only on how much mass there is and how far away you are, not its shape.
Swap the Sun for a black hole of the same mass. Earth keeps orbiting exactly as before, cold and dark but not pulled in.
The difference is how close you can go. A star's surface stops you early. A black hole lets you near the center, where gravity soars.
Far from the hole, objects can orbit steadily, like planets around the Sun. Stray inside the innermost stable orbit and gravity pulls you in.
So a black hole isn't a hungry drain; it's a heavy object whose danger lives only up close, and from far away it's just gravity as usual.