Where does Barney come from?

Do they ever explain on the show where Barney comes from or how he has his imagination powers? Also if he is a stuffed animal when not big, what does he do in that time period? Does he reside in another realm, since Baby Bop and BJ and other characters disappear as they walk off? Does anyone “own” Barney as a stuffed animal or do the kids take turns bringing him home? Would be interesting to explore the Barney mythology