Short answers, pulled from the story.
Egyptian mythology is the collection of myths from ancient Egypt that describe the actions of the gods as a means of understanding the world. These myths appear in religious writings such as hymns, ritual texts, funerary texts including the Pyramid Texts and Coffin Texts, and in temple decoration, as well as in non-religious literature and private magical texts.
Maat refers to the fundamental order of the universe in Egyptian belief, established at the moment of creation and distinguishing the ordered world from the primordial chaos that surrounds it. It encompasses both proper human behavior and the normal functioning of natural forces. The pharaoh was regarded as the most important human maintainer of maat.
The most important mythic episodes include the creation myths, in which the gods form the universe out of primordial chaos; the stories of Ra's reign on earth and his daily journey through the sky and the Duat; and the Osiris myth, which concerns the struggles of Osiris, Isis, and Horus against Set. The Osiris myth is described as the most elaborate of all Egyptian myths and had the most widespread influence in Egyptian culture.
The Pyramid Texts are the first major written source of Egyptian mythology, consisting of several hundred incantations inscribed inside pyramids beginning in the 24th century BC. They were the first Egyptian funerary texts, intended to ensure that the kings buried in the pyramids would pass safely through the afterlife. Many of the texts are believed to be much older than their first known written copies.
Egyptian myths differ and apparently contradict each other because they were not meant as fixed, dogmatic narratives. The Egyptologist Henri Frankfort argued in the 1940s that apparently contradictory ideas are part of a deliberate multiplicity of approaches the Egyptians used to understand the divine realm. Different versions of the same myth express different symbolic aspects of the same phenomenon, and local cults also developed distinct theologies centered on their own patron gods.
The Osiris myth is the most elaborate Egyptian myth and influenced religious rituals, funerary practices, and art throughout Egyptian history. Funerary rites such as the Opening of the Mouth ceremony evoked Osiris' resurrection, and private magical spells called upon Isis to heal the sick as she healed Horus. In art, scenes depicting the resurrection of Osiris appear in tombs and temples, and the Eye of Horus became one of the most common protective amulet shapes in Egyptian life.