Black Hole

A Black Hole is region a region of spacetime exhibiting gravitational acceleration so strong that nothing (no particles or even electromagnetic radiation such as light) can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.

--Event Horizon--

In astrophysics, an event horizon is a boundary beyond which events cannot affect an observer. John Michell proposed in 1784 that near compact massive objects, gravity would increase to the extent that even light cannot escape.