Hell, sometimes called The Pit or Prison House, is a place where those who have rejected the teachings of God and His Son are assigned until the Second resurrection. Psalms 9:17 calls these the wicked. Hell is a place of instruction, for Christ went and preached unto the spirits in prison. Peter 3:18 - 20 Those who have totally rejected the word of God will go to the lake of Fire and brimstone, which is the second death. John the revelator tells us, He (Jesus) has the keys of Hell and of death. Revelations 1:18
The Gospel is Preached to those in Hell:
(Eph 4:9 KJV) Now that he ascended, what is it but that he also descended first into the lower parts of the earth?
(1 Pet 3:18-20 KJV) For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit: By which also he went and preached unto the spirits in prison; Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water.
(1 Pet 4:6 KJV) For for this cause was the gospel preached also to them that are dead, that they might be judged according to men in the flesh, but live according to God in the spirit.
(Rev 1:18 KJV) I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
(Isa 61:1 KJV) The spirit of the Lord GOD is upon me; because the LORD hath anointed me to preach good tidings unto the meek; he hath sent me to bind up the brokenhearted, to proclaim liberty to the captives, and the opening of the prison to them that are bound;