Latter-day revelations speak of hell in at least two ways. First, it is another name for spirit prison, a temporary place in the postmortal world for those who died without a knowledge of the truth or those who were disobedient in mortality. Second, it is the permanent location of Satan and his followers and the sons of perdition, who are not redeemed by the Atonement of Jesus Christ.
Spirit prison is a temporary state in which spirits will be taught the gospel and have the opportunity to repent and accept ordinances of salvation that are performed for them in temples (see D&C 138:30–35). Those who accept the gospel may dwell in paradise until the Resurrection. After they are resurrected and judged, they will receive the degree of glory of which they are worthy. Those who choose not to repent but who are not sons of perdition will remain in spirit prison until the end of the Millennium, when they will be freed from hell and punishment and be resurrected to a telestial glory (see D&C 76:81–85).
Those who are not redeemed by the Atonement are in outer darkness, which is the dwelling place of the devil, his angels, and the sons of perdition (see D&C 29:36–38; 76:28–33). Sons of perdition are those who receive "no forgiveness in this world nor in the world to come—having denied the Holy Spirit after having received it, and having denied the Only Begotten Son of the Father, having crucified him unto themselves and put him to an open shame" (D&C 76:34-35; see also D&C 76:31–33, 36–37). Such individuals will not inherit a place in any kingdom of glory; for them the conditions of hell remain (see D&C 76:38; 88:24, 32).
—See True to the Faith (2004), 81
"I Have a Question"
H. Donl Peterson, Ensign, Apr. 1986, 36–38
What is the meaning of the Book of Mormon scriptures on eternal hell for the wicked?
Guide to the Scriptures
Bible Dictionary, 699–700
"The Postmortal Spirit World"
Gospel Principles, Chapter 45
Encylopedia of Mormonism
(Please note that the contents of the Encyclopedia of Mormonism, a joint product of Brigham Young University and Macmillan Publishing Company, do not necessarily represent the official position of The Church of Jesus Christ of Latter-day Saints.)