Mormon.org answers this question well.
“Death is not the end. Death is really a beginning—another step forward in Heavenly Father’s plan for His children. Someday, like everyone else, your physical body will die. But your spirit does not die, it goes to the spirit world, where you will continue to learn and progress and may be with loved ones who have passed on.
Death is a necessary step in your progression, just as your birth was. Sometime after your death, your spirit and your body will be reunited—never to be separated again. This is called resurrection, and it was made possible by the death and Resurrection of Jesus Christ (see 1 Corinthians 15:20-22).”
Related Articles and Links:
Mormon.org – Purpose of Life
Mormon.org – God’s Plan of Happiness
Plan of Salvation
Life After Death – Part 1
Life After Death – Part 2