Hi Essorant. One definition might be it is all the matter, energy, space and time that exists from the tinniest bit of matter and energy to the extent of the farthest stars.
Or were you thinking of something more philosophical?
As to your next questions: God created the universe described as "the heavens and the earth" in Gen. 1:1.
AS to "where does it go to?", there are at least two views of thought:
1) In Rev.21 we read of a "new heaven and new earth; for the first heaven and earth had passed away.." RSV. The earth and the surrounding heaven (atmosphere) will be new while the vast reaches of the stars remain unchanged. Thus, the universe doesn't go anywhere.
2) There will be completely a new universe with the present one burning up.
The "burning up" comes from 2 Pet.3:10 "..the
heavens will pass away with a loud noise, and
the elements will be fire, and the earth and the works that are upon it will be burned up.
Why the whole universe recreated? Paul says
in Rom. 8:19-23 "For the creation waits with
eager longing for the revealing of the sons of God; for the creation was subject to futility, not of its own will but by the will
of him who subjected it in hope; because the
creation itself will be set free from its bondage to decay and obtain the glorious liberty of the children of God." This seems to imply that the whole creation will be made new.