Niflheim (or Niflheimr) ("Mist Home", the "Abode of Mist" or "Mist World") is one of the Nine Worlds and is a location in Norse mythology which overlaps with the notions of Niflhel and Hel. The name Niflheimr only appears in two extant sources, Gylfaginning and the much debated Hrafnagaldr Óðins. According to Gylfaginning, it was one of the two primordial realms, the other one being Muspelheim, the realm of fire. Between these two realms of cold and heat, creation began. Later, it became the location of Hel, the abode of those who did not die a heroic death.