Death, in many cultures, is the ultimate transition that life is leading up to. So it is no surprise that among the core series of sacraments, known as Sanskara, or rituals of perfection, the final rite comes in the funerary process of the Antim Sanskar. The importance of perfecting yourself in Hindu culture stems from the belief that your actions in life determine whether you are granted happiness or misery in your life.
The sum of your actions will ultimately get wiped clean at the time of death. As part of the Antim Sanskar the sava, or body, must be cremated after the sukshma sareera — the consciousness or soul — has left its physical vessel. In this way, the sukshma sareera represents the actions that you have taken in life, which in turn will reflect on the nature of rebirth that the soul will receive.