The Netherworld was the Djelibeybian version of the Afterlife.
In these beliefs, after a person dies their soul is led into a hall of judgment in Duat by Anubis (god of mummification) and the deceased's heart, which was the record of the morality of the owner, is weighed against a single feather representing Ma'at (the concept of truth and order). If the outcome is favorable, the deceased is taken to Osiris, god of the afterlife, in Aaru, but the demon Ammit (Eater of Hearts) – part crocodile, part lion, and part hippopotamus – destroys those hearts whom the verdict is against, leaving the owner to remain in Duat. A heart that weighed less than the feather was considered a pure heart, not weighed down by the guilt or sins of one's actions in life, resulting in a favorable verdict; a heart heavy with guilt and sin from one's life weighed more than the feather, and so the heart would be eaten by Ammit. An individual without a heart in the afterlife in essence, did not exist as Egyptians believed the heart to be the center of reason and emotion as opposed to the brain which was removed and discarded during mummification. Many times a person would be buried with a "surrogate" heart to replace their own for the weighing of the heart ceremony.