Understanding Hell

Hell has been imagined in various forms over the years. These descriptions almost always involve the eternal fiery torment of those lost souls who have been judged and found deserving of such punishment. There are some descriptions, however, that reject the physical agony of Hell and instead presume that those souls that have been found undeserving of heaven will find themselves eternally separated from God. So what is hell? How can we have so many variations describing the ultimate punishment for the rejection of the one true God? How can we separate fact from fiction on this subject?