A black hole is a point of infinitely dense space with such a high density that no matter or energy may escape. It is formed when a supermassive star supernovaes. It has enough gravity, however, that it will collapse inward on itself. Normally, when this happens, the Palaui Force cannot resist
gravity's push (this means that electrons orbiting a nucleus of an atom are pushed inward to the nucleus), and forms
neutronium (a superdense form of matter made of only neutrons). Normally, this dense ball of matter forms a neutron star, but in extreme cases, the ball of matter is so dense that it collapses inward on itself. Nothing can stop this collapse once it has started, and it will not end until the matter reaches a point of 0 dimensions (0 feet high, wide, and deep). This forms
the singularity of the black hole. There is also a "point of no return", or
the event horizon. Once you have crossed this sphere circling the black hole, you will be ripped apart atom by atom, and strung out to an infinite length (called
spaghettification). This process will take an infinite amount of time, and nothing will ever get you out. There are also two different types of singularities (that we know about). There are stationary and spinning. In a stationary singularity, the singularity is a single point where the curvature becomes infinite. However, in a spinning singularity, said singularity becomes 2 dimensional, stretching in both space & longitude (this drags space-time surrounding the event horizon, something known as frame dragging). This spinning space-time surrounding the event horizon is known as an
ergosphere, which is shaped like an ellipsoid (this is an
ellipse, but in 3 dimensions (think about how pluto doesn't orbit the sun right, and you have the idea, represented by the formula {x^2\a^2}+{y^2\b^2}+{z^2\
c^2}=1).) This presents a great opportunity for space flight, as a ship grazing the surface of the ergosphere could be launched off at reletavistic speeds.
The singularity is most likely a ring shape, instead of a dimensionless sphere. If you fell into a spinning black hole, it is possible you would not
spaghettify. If you fell through the inner horizon (the ring singularity) perfectly distanced from all points on the ring, you might make it.
Now, you figure that matter has to go somewhere, and it (theoretically) is ejected at
a white hole.
A white hole is described as "a postulated celestial body that is the time reversal of a black hole. While a black hole acts as a point mass that attracts and absorbs any nearby matter, a white hole acts as a point mass that repels or (perhaps) even ejects matter." Now, there is no proof of white holes, and it is doubtful you could pass through one (see wormhole, because of a paper published in 1962 by John A. Wheeler and Robert W. Fuller proving that
Schwarzschild wormholes are disconnected instantaneously after they are formed, not allowing even light to pass through). I've said waaaaay too much, so I'm going to shut up now. Have a nice day.