John Mitchell was the first to put forth the idea of black holes when he wrote Henry Cavendish about the matter. A mathematician named Pierre-Simon Laplace promoted the same concept as Mitchell, later in 1796. No one has completely understood the whole concept. Black holes have been a major discussion topic since then.
A black hole is a mass that is so enormous that light could not escape the gravitational force of it. In able to escape one’s pull such as the moon you must know what the Escape velocity is. Escape velocity is the speed at which the kinetic energy plus the potential energy of the masses gravity is zero. Also a key term to help you understand black holes is Schwarzschild radius, which is the radius of a body where its gravitational forces are greater than the ability of matter and energy to escape creation a black hole. One method used to detect black holes is looking for their gravitational influence on objects such as stars. The only other method used is to observe matter that is falling into black holes. As matter falls in the black hole it settles in a ring around it. To find the mass of the black hole you have to use measurements of the movement by the objects.
Black holes are a very unique and complex subject. Scientists still today do not completely understand the concept of them. Black holes will always be a very important part in science and scientists will never stop trying to find more and more black holes.