Black holes are so dense and their attraction is so strong that they can not escape any form of radiation – not even light.
They act as intense sources of gravity, sucking dust and gas around them.
It is believed that their intense magnetism is what orbits stars in galaxies.
How they are formed is still poorly understood.
Supermassive black holes are incredibly dense areas at the center of galaxies whose masses can make billions of hours of sunlight. They cause burglaries in space-time (the artist's impression), and even light can not escape attraction
Astronomers believe that they could form when a large gas cloud, up to 100,000 times larger than the sun, enters black hole collapses.  Many of these black hole cores then merge into much larger supermassive black holes that are at the center of every known massive galaxy.
Alternatively, a supermassive black hole grain could come from a giant star, about 100 times the mass of the Sun, which eventually forms a black hole after the fuel runs out and breaks down.
When these giant stars die, they also pass into the supernova, a huge explosion that tolerates the matter from the outer layers of the star's outer space.