What is Event Horizon of a Black Hole?

What I mean to say is, how are the characteristics of event horizon related to Space-Time?

Formally, an event horizon is the boundary of a region of spacetime that's not in the causal past of future null infinity. In other words, the boundary of a region from which even idealized light rays cannot escape to infinity. Whenever the event horizon is smooth, it is also null hypersurface--i.e., the direction perpendicular to it is a light ray.

Because the event horizon is defined in terms of the infinite future, the definition is very non-local, and one would need to know the entire future history to be sure where the event horizon is. As such, it is only one of a half-dozen different types of horizons used to study black holes.

Though the event-horizon itself is a three-dimensional hypersurface in spacetime, it can also be viewed as an evolving two-dimensional membrane made of a viscuous electrically conducting fluid with finite temperature and entropy but zero thermal conductivity.