Where do black holes come from?
Black holes are formed when stars collapse on themselves. The collapsed or dead star generates such immense gravity that it attracts everything from hundreds of millions of miles around
including light. And because there is no light in them they are virtually invisible. Hence the name black hole.
What do they do?
The other amazing thing about black holes is that all matter absorbed into the hole disappears. Unlike on earth, where stuff is just moved or transformed into something else (burned wood to heat and ash or evaporated seawater to rain etc), in black holes everything vanishes. Its bizarre and strange and astonishing, and somewhat beyond comprehension. Apparently the only way to escape a black hole is through quantum tunnelling - but that would be telling.
Who discovered black holes?
A British philosopher, John Michell was the first to theorise about the existence of black holes way back in 1783. He contemplated the effect a compacted star would have on the light particles it emits and worked out a mathematical solution to escape a stars gravity using Newtons laws. Needless to say, they didnt get out much.
How did they get their name?
Michell first used the term dark stars naming the stars that had collapsed and died. In the 1960s Karl Schwartzschild calculated their existence and they were renamed Schwartzschild singularities. It wasnt until 1969 that John Wheeler, who was studying Einsteins theory of relativity, named the collapsed stars black holes, apparently upsetting the French who wanted to go for hidden star. But the catchier black hole stuck.
What happens to them?
In the 1970s, Stephen Hawking, one of the planets biggest names in astrophysics, and one of the worlds sharpest brains discovered that black holes slowly evaporate over time. Not sure how he worked that one out.