A black hole is a region of space where the gravitational pull is so strong that nothing, including light, can escape from it. This happens when a massive star dies and collapses in on itself, creating a singularity with infinite density and zero volume.
Black holes form when massive stars run out of fuel and collapse under their own gravity. This collapse causes the core of the star to become incredibly dense, creating a black hole. Alternatively, black holes can also form from the merging of two or more smaller black holes.
The event horizon is the point of no return for anything that enters a black hole. It is the boundary where the escape velocity is equal to the speed of light, meaning that even light cannot escape from it. Once something crosses the event horizon, it is pulled into the black hole and cannot escape.
Black holes do not emit any light as they absorb all forms of electromagnetic radiation that come their way. However, they can be detected through the radiation emitted by matter falling into them, as well as the effects of their strong gravitational pull on surrounding matter.
It is currently believed that nothing can survive entering a black hole. The gravitational forces are so strong that they would tear apart any object, including atoms, as it gets closer to the singularity. However, this is still a topic of ongoing research and there are theories that suggest some forms of matter may be able to survive the journey.