Question

what is a white and black hole

Answer 1

A black hole is a hole of space.
Einstein has said that one can travel in Time by using it.And it takes a lot of mass and transfer into a very little thing.

Answer 2

Black hole:-

A black hole is a region of space time where gravity is so strong that nothing-no particles or even electromagnetic radiation such as light-can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a blackhole.

White hole:-

In generally relativity,a white hole is a hypothetical region of spacetime and singularity which cannot be entered from the outside , although energymatter,light and information can escape from it. White holes appear in the theory of eternal black holes.