A black hole is a region in space where the gravity is so strong that nothing, not even light, can escape. It is a region where matter collapses due to the heat and pressure supplied by the fusion of the material within the object. In a star, for example, if the fusion of the material within it is less than the gravitational pull inward, the star will collapse, and if it is massive enough, it will form a black hole. Nothing can escape a black hole because of the intense gravitational field. Nothing, not even light can escape because the gravitational force is crunching down an object into an incredibly small space. .
The gravitational force of an object in space depends on the size of the object and the mass of the object. Increasing the mass of the object or decreasing the size of the object will result in an increase of gravitational force. When the mass of an object is decreased or the size is increased, the gravitational force will decrease. .
As far as we know, black holes consist of only two things: event horizons and singularities. If you envision a black hole as a sphere, the surface of the sphere would be the event horizon. Behind the surface of the black hole or, event horizon, the inward pull of gravity is so strong that no information about the interior of the black hole can escape to the outer universe. The singularity lies at the center of the black hole. Here, the infinitely strong gravitational force is so great that matter is crushed into infinite destiny, creating an infinite curvature of space-time. A singularity is simply a point with no dimensions, surrounded by a region in space that is completely dark. The region interior to a black hole's event horizon appears black because the gravity is so strong that the escape velocity equals the speed of light. There is no satisfactory theory for what happens at and beyond the singularity; Time and space no longer have any meaning and cease to exist as we know them.