Black Holes are regions in space which have an extraordinarily strong gravitational pull that prevent even light from escaping from them. Since light doesn't escape, the black hole doesn't reflect light and hence the name 'black' hole.
A black hole is created as a result of the collapse of a star. It has a single entry surface which is known as the event horizon. Through the event horizon, an object can enter but it can never come out.
Black holes have been a subject of research as well as curiosity for scientists since a long time. In scientific terms, a black hole could be described as a substance whose escape velocity is greater than the speed of light.
Karl Schwarzschild was the first scientist who used Einstein's theory of relativity to develop the concept of a black hole.