Heaven is the place where God lives, where we lived before this life, and where we can live again. The Church of Jesus Christ of Latter-day Saints (sometimes inadvertently referred to as the “Mormon Church) teaches some very specific doctrines concerning heaven. The Church of Jesus Christ’s teachings about heaven are central to the Plan of Salvation, or the Plan of Happiness, by which each of us came to earth, received a body, is tested, and can return to live with God again.
Spirit Paradise and Spirit Prison
Latter-day Saints believe that when a person dies, he or she goes to either paradise or spirit prison. People who have accepted the gospel of Jesus Christ and made and kept the necessary covenants while on earth go to paradise. People who have not accepted and lived the gospel, either because they did not live it, rejected it, or did not have the opportunity to hear it, go to spirit prison. Paradise and spirit prison are active places. Spirits from paradise go to teach other spirits the gospel. Spirits in spirit prison can accept the gospel of Christ, and their ordinances (religious ceremonies) can be done vicariously for them by people on earth.
Paradise and spirit prison aren’t permanent. Jesus Christ will return to the earth, and all the people whose spirits are in paradise or spirit prison will be resurrected (reunited with their perfected physical bodies). Eventually, all people who have lived, do live, or will live on earth will be judged by Jesus Christ, and then “receive an eternal dwelling place in a specific kingdom of glory.” 
Kingdoms of Glory
Latter-day Saints believe that heaven is split into three degrees or kingdoms: the Celestial, Terrestrial, and Telestial Kingdoms. We also believe in perdition, a kingdom that is not a kingdom of glory. The Church of Jesus Christ teaches that “the glory we inherit will depend on the depth of our conversion, expressed by obedience to the Lord’s commandments. It will depend on the manner in which we have ‘received the testimony of Jesus’ (Doctrine and Covenants 76:51).”  Latter-day Saints believe that Jesus taught the principle of kingdoms of glory in John 14:2 when He said, “In my Father’s house are many mansions,” and that the prophet Joseph Smith received further revelation about the kingdoms of glory. Joseph Smith’s revelation is recorded in Section 76 of the Doctrine and Covenants.
- Celestial Kingdom. The celestial is the highest of the three degrees of glory, and is where Heavenly Father and Jesus Christ live. People who inherit this kingdom of glory will dwell forever in the presence of God and Jesus Christ. This is the ultimate goal: to inherit celestial glory. The Doctrine and Covenants states that people who inherit the celestial kingdom are “just men made perfect through Jesus the mediator of the new covenant” who “received the testimony of Jesus” (D&C 76:51, 69). A person cannot reach the celestial kingdom through works alone; the grace of Jesus Christ is also necessary. Latter-day Saints also believe that to inherit celestial glory, one must have made all of the necessary covenants (promises with God) and performed the ordinances that He has commanded. These include the baptismal covenant and other sacred temple covenants, including marriage.
- Terrestrial Kingdom. The Church of Jesus Christ teaches: “Individuals in the terrestrial kingdom will be honorable people ‘who were blinded by the craftiness of men’ (D&C 76:75).” Included in this group are members of The Church of Jesus Christ who were less valiant in following the Savior, and individuals who rejected the gospel in mortality but accepted it in the spirit world. Individuals who did not have the opportunity to receive the gospel on earth but accept it in the spirit world will not inherit this kingdom; they can still inherit the celestial kingdom.
- Telestial Kingdom. The telestial kingdom is for people who “received not the gospel of Christ, neither the testimony of Jesus” (D&C 76:82). They rejected the gospel and did not accept Jesus Christ.
- Perdition. Perdition is not a kingdom of glory and is reserved only for people who accepted the fulness of the gospel and then willfully rejected their knowledge. There will not be many individuals who meet the requirements to be sent to perdition.
Works and Grace
Jesus Christ will judge all of us according to our actions, and then we will go to a kingdom to dwell eternally. It is up to us to do all we can in this life to reach the celestial kingdom; but not one person, except the Savior, can reach the celestial kingdom alone. Latter-day Saints believe in the importance of both works and grace; we need both to reach celestial glory.
The Importance of Faith
Latter-day Saints have a lot of additional revelation about heaven, which is very comforting, especially upon the death of a loved one. It is comforting to know that our ancestors can dwell in the same glory we can and that the gospel of Jesus Christ includes everyone. It is also humbling to realize that we cannot attain our goal of celestial glory without the grace of our Savior.
However, with all that Latter-day Saints know about heaven and life after death, there is and will always be some uncertainty. What can be frightening about life after death is that it is unknown, and we can be unsure of exactly what it will be like. We may be uncertain how complicated family relationships might be worked out, or unsure of what our family members are doing on the other side of the veil.
I believe that these worries, while they may be legitimate, needn’t worry us right now. Heavenly Father is ultimately in charge and with His perfect knowledge and understanding will work everything out. I believe that we know enough to help us get back to Heavenly Father. Sure, there are things about heaven we don’t know. But that’s okay, because if we knew everything right now, we wouldn’t need faith.