black hole

Event Horizon: This is the boundary around a black hole beyond which nothing can escape. Once an object crosses the event horizon, it is effectively trapped inside the black hole, and no information about it can be observed from outside.

Singularity: At the center of a black hole lies a point called the singularity, where all the mass of the collapsed star is concentrated into an infinitely dense and tiny point. The laws of physics, as we currently understand them, break down at this point.