Much like a black body in thermodynamics, a black hole is a region of space that pulls everything and prevents anything from escaping, even light. The reason it is called a "black" hole is because it sucks up all the light that hits its border and reflects nothing. Formed when an amply compact mass deforms space and time, a black hole has a defined surface known as the "event horizon" which marks the point of no return. Little is known about black holes but several scientists in history have developed their own theories about their properties and structures.
Here is a list of 25 crazy facts about black holes.