text: In formal scientific terms, a black hole is called a "singularity."  It is a point.  The spherical object often thought of as a black hole is the "event horizon" that is centered on the singularity.\n\nThe event horizon is the sphere within which the escape velocity is greater than the speed of light; nothing can exceed the speed of light, so nothing can get out of the event horizon.  \n\nHowever, black holes emit "Hawking radiation," as follows.  "Consider a virtual electron-positron pair produced just outside the event horizon. Once the pair is created, the intense curvature of spacetime of the black hole can put energy into the pair. Thus the pair can become non-virtual; the electron does not fall back into the hole. There are many possible fates for the pair. Consider one of them: the positron falls into the black hole and the electron escapes. According to Feynman's view we can describe this as follows:\nThe electron crosses the event horizon travelling backwards in time, scatters, and then radiates away from the black hole travelling forwards in time." [see the fourth link]\n\nBlack holes loose mass by emitting Hawking radiation until all the mass has been radiated.  (Remember that mass can be converted to energy according to E = m x c^2.)  \n\nWhen you do the math, it turns out that each black hole will "evaporate" to nothing within a certain time that depends upon its mass, larger black holes having longer lifespans.\n\nA black hole that initially weighs 2 x 10^5 kg (200  metric tonnes) will live one second.  A black hole having a mass equal to the sun will live 10^67 years. (Assuming the Universe does not end before then!)\n\nSo, the short answer to your question is that the mass that falls into a black hole is converted to energy and radiated into space by the black hole.