A black hole is a region in space where the pulling force of gravity is so intense it swallows anything near it, including light. Mainly feared in pop sci-fi, they in fact are an essential part of the structure of the universe.
The strong gravity that comes into play with black holes occurs because matter has been pressed into a tiny space. This can happen at the end of a star's life, making some black holes the result of dying stars. Scientists believe the smallest black holes came about when the universe began. There are black holes at the center of most galaxies, including our own.
Because no light escapes, black holes are invisible to us. But space telescopes with special instruments can help astronomers find black holes.
In this artist's illustration, a supermassive black hole, millions or even billions times the mass of our sun, is seen at the center, surrounded by matter flowing onto the black hole in what's called an accretion disk. This disk forms as the dust and gas in the galaxy fall onto the hole, attracted by its gravity. Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole's spin, according to NASA.