Duat also spelled Tuat is the Egyptian idea of the underworld(also called Akert, Amenthes, or Neter-khertet). To the Egyptians the underworld was divided into sections filled with dangers that the Egyptian Soul had to pass through. This is the same realm that Ra was believed to pass into each night and battle Apophis. The Egyptian Underworld is described in many funerary texts found in tombs of mummies believed to help guide them through death.
In Duat is where the famous Weighing of the Heart is displayed. Where the soul shown as a heart is weighed on the scales of Anubis against the feather of Ma'at.
The Egyptian idea of the underworld influenced many other ideas of life after death in other cultures. Ammit was believed to eat the souls of people whose heart did not weigh the exact weight of Ma'at's feather. It was thought that the heat was then eaten by a lion.