What is the event horizon in a black hole?

Does everything that enters it disappears or does it just disintegrate into microscopic particles? And if matter that goes over the event horizon leaves the universe where does it go?What is the event horizon in a black hole?
The event horizon is kind of a conceptual barrier, rather than a physical one. Simply put, an observer outside the event horizon will never be able to detect any event occurring inside the event horizon. There is nothing we can observe inside a black hole; we can only see what's going on up to the event horizon.



Suppose you and I were orbiting a black hole in our respective spaceships. We could radio each other and wave out our view ports to each other. If I began to descend slowly toward the black hole, however, eventually I would get so close to the gravity well that light and radio waves would start getting pulled into the black hole. At some point, I would disappear from your view, and my actions thereafter would be hidden from this universe (although I'm sure we can both guess what they would be!), though all of my matter would still be -in- this universe.



Actually, because of the behavior of light, you might see my ship grow dimmer and more red, and move slower and slower, until my image stopped, "stuck" to the event horizon forever. And the above is not a complete explanation, because it's known that black holes emit X-rays, but the exact mechanism is a matter of debate.
Epic dude is actually very much incorrect, might I add, because due to the uncertainty principle, one cannot accurately determine both the position and velocity of a particle, thus there must be what we call vacuum fluctuations. Rather, the event horizon of a black hole includes the theoretical method of entropy, and is, to put quite simply, the edge of a black hole, the boundary of the region in spacetime from which it is not possible for a particle nor any form of energy, matter, or radiation, can escape the gravitational force of the "black hole".What is the event horizon in a black hole?
The black hole is in our universe therefore the matter that enters stays in our universe.



The evidence of that is that the mass that enters the black hole continues to participate in the gravitational effect of the black hole and that gravitational effect affects our universe (therefore, it does not leave).



The event horizon represents the limit of our interaction with the "object" from our frame of reference. Any information from an object that is "inside" the event horizon will never reach us.



The same way that information about the part of the universe that is beyond the limit of the Visible Universe (the portion we can see) will never reach us -- in that last case, we are inside the horizon and we can't get information about the outside.



We do not "know" what happens to matter that enters the event horizon, going into a black hole, but we can apply the knowledge we have about how particles and sub-particles (and sub-sub-...) to try and understand what happens.



There is one snag: we are not sure we fully understand how time really works inside a black hole. As far as we can tell (but we do not know for sure) and object falling into the black hole keeps accelerating forever, but never reaches the centre.



That is because space is expanding faster and faster (we think) as one tries to approach the singularity.



What we do know is that the gravitational gradient (a.k.a. tidal force) gets very steep, especially for smaller black holes, so that even atoms are ripped apart by the tidal tension (one side of the atom gets a lot more gravity than the other), and even the particles themselves (e.g., a proton) can get ripped apart. When that happens (outside the event horizon), the ripping apart causes very high-energy photons to be emitted (X-rays, gamma rays). They represent the force that tried to keep the particle in one piece... until it got ripped apart.



If the gradient is smooth enough for particles to survive, then they can enter the event horizon before being ripped apart. However, we think that they would eventually be ripped apart to pure energy (but we would never see the resulting photons, as they can't escape back to our side of the horizon).
It's the surface of equal distance from the singularity at which the escape velocity is equal to the speed of light. Everything "disappears" from the observable universe when the event horizon is crossed, it isn't disintegrated.What is the event horizon in a black hole?
The event horizon of a black hole is also known as the "point of no return" it is called this because it is at this point where nothing can escape the black hole's vicinity, not even light.
Neither; the matter is just compressed at it's centre into a singularity. Some theories sugest that there are light holes that give out that matter from a connected black hole
radius of event horizon is given as

2GM / (c^2).