Duat (Ancient Egyptian: dw?t, Egyptological pronunciation "do-aht", Coptic: , also appearing as Tuat, Tuaut or Akert, Amenthes, Amenti, or Neter-khertet) is the realm of the dead in ancient Egyptian mythology. It has been represented in hieroglyphs as a star-in-circle: ?. The god Osiris was believed to be the lord of the underworld. He was the first mummy as depicted in the Osiris myth and he personified rebirth and life after death. The underworld was also the residence of various other gods along with Osiris. The Duat was the region through which the sun god Ra traveled from west to east each night, and it was where he battled Apophis, who embodied the primordial chaos which the sun had to defeat in order to rise each morning and bring order back to the earth. It was also the place where people's souls went after death for judgment, though that was not the full extent of the afterlife. Burial chambers formed touching-points between the mundane world and the Duat, and the (Egyptological pronunciation: "akh") "the effectiveness of the dead", could use tombs to travel back and forth from the Duat.
Each night through the Duat the sun god Ra travelled, signifying revivification as the main goal of the dead. Ra travelled under the world upon his Atet barge from west to east, and was transformed from its aged Atum form into Khepri, the new dawning sun. The dead king, worshipped as a god, was also central to the mythology surrounding the concept of Duat, often depicted as being one with Ra. Along with the sun god the dead king had to travel through the Kingdom of Osiris, the Duat, using the special knowledge he was supposed to possess, which was recorded in the Coffin Texts, that served as a guide to the hereafter not just for the king but for all deceased. According to the Amduat, the underworld consists of twelve regions signifying the twelve hours of the sun god's journey through it, battling Apep in order to bring order back to the earth in the morning; as his rays illuminated the Duat throughout the journey, they revived the dead who occupied the underworld and let them enjoy life after death in that hour of the night when they were in the presence of the sun god, after which they went back to their sleep waiting for the god's return the following night.
Just like the dead king, the rest of the dead journeyed through the various parts of the Duat, not to be unified with the sun god but to be judged. If the deceased was successfully able to pass various demons and challenges, then he or she would reach the weighing of the heart. In this ritual, the heart of the deceased was weighed by Anubis against the feather of Maat, which represents truth and justice. Any heart that is heavier than the feather was rejected and eaten by Ammit, the devourer of souls, as these people were denied existence after death in the Duat. The souls that were lighter than the feather would pass this most important test, and would be allowed to travel toward Aaru, the "Field of Rushes", an ideal version of the world they knew of, in which they would plough, sow, and harvest abundant crops.
What is known of the Duat derives principally from funerary texts such as the Book of Gates, the Book of Caverns, the Coffin Texts, the Amduat, and the Book of the Dead. Each of these documents fulfilled a different purpose and give a different conception of the Duat, and different texts could be inconsistent with one another. Surviving texts differ in age and origin, and there likely was never a single uniform conception of the Duat, as is the case of many theological concepts in ancient Egypt.
The geography of Duat is similar in outline to the world the Egyptians knew. There are realistic features like rivers, islands, fields, lakes, mounds and caverns, but there were also fantastic lakes of fire, walls of iron and trees of turquoise. In the Book of Two Ways, one of the Coffin Texts, there is even a map-like image of the Duat. The Book of the Dead and Coffin Texts were intended to guide people who had recently died through the Duats dangerous landscape and to a life as an . Emphasized in some of these texts are mounds and caverns, inhabited by gods, demons or supernatural animals, which threatened the deceased along their journey. The purpose of the books is not to lay out a geography, but to describe a succession of rites of passage which the dead would have to pass to reach eternal life.
In spite of the many demon-like inhabitants of the Duat, it is not equivalent to the conceptions of Hell in the Abrahamic religions, in which souls are condemned with fiery torment; the absolute punishment for the wicked, in ancient Egyptian thought, was the denial of an afterlife to the deceased, ceasing to exist in form. The grotesque spirits of the underworld were not evil, but under the control of the gods, being present as various ordeals that the deceased had to face. The Duat was also a residence for various gods, including Osiris, Anubis, Thoth, Horus, Hathor, and Maat, who all appear to the dead soul as it makes its way toward judgement.