Hell
In the English translation of the Bible's Old Testament, the word hell normally corresponds to the Hebrew sheol, which was simply the place of the dead. But in the Greek New Testament the word used is either Gehenna (the garbage dump outside the walls of Jerusalem where fires were kept eternally burning to consume the refuse and keep down the stench) or Hades, the Greeks' dark, gloomy underworld. The modern English word appears to derive most directly from "Holle" or "Hela" or "Hel", goddess of the dead in Germanic/Norse mythology. When the Anglo-Saxons converted to Christianity, the existing word in the language was reused in this new context and applied to the meanings given above.
Etymology aside, hell is now known to be a place where the souls of the wicked are punished eternally for all the sins they perpetrated during their lifetime on Earth. According to Christianity, the only way to avoid hell is to know, love, and serve God and rely on His forgiveness. Even after 10,000 years in hell, the sinner has not even begun his punishment in the educationally hot fires. Separated from God, all that remains is despondence and fires and the devil.
The Christian and Muslim religious traditions often emphasize the Gehenna aspect: Hell is extremely hot and filled with fire and brimstone. Opinion varies on the question of whether, while hell itself is eternal, experience of it purges away the sins of sufferers to the point of eventual redemption. See purgatory. A minority of Christians do not believe in an eternal hell, believing instead that the souls of the wicked are annihilated. This view is referred to as Annihilationism.