This is a question that I am sure almost everyone has pondered at one time or another.
Today there are many books on the subject.
There are many stories of near death experiences. Many people have come close to death and have had visions of out of body experiences. Some have seen long dead relatives, or have come into a place of bright light and experienced peace. Some also have testified of going to a cold dark place full of torments and burning flames. However, I don't doubt that God has given many honest folks visions of heaven and hell, as well as actual experiences of what it is like to approach death.