For questions about a region of space time where gravity is so strong that nothing, not even light, can escape it.
A black hole is a region where a massive object has been squeezed into such a small space that the escape velocity is greater than the speed of light. The radius of this area is the Schwarzschild radius and the region is often called the Event Horizon.
Black holes may be formed from the collapse of massive stars, and may have masses ranging from anywhere from a few solar masses to many thousands of solar masses. They are thought to lose mass and eventually disappear through Hawking radiation.
Since no known force can stop a core collapse after gravity achieves this strength, Relativity predicts that the core is thought to collapse to a location of infinite density and zero size called a singularity. However, Relativity and Quantum Mechanics cannot be combined in a way to determine what might really happen at the Singularity.
Consider also the astronomy tag.