Black holes: an extreme boundary
A black hole has a region where gravity is so strong that even light cannot escape. The boundary is called the event horizon.
We learn about black holes by studying nearby matter, light, and other signals. They do not roam around vacuuming up the whole universe.
Wonder about this
Does being near a black hole mean every distant object must fall into it?
A science clue
No. Objects far enough away can orbit; mass, distance, and motion matter.