The Prologue is a short euhemerising frame that derives the Norse gods from human beings: the Aesir are men from Troy, Odin a migrating king whose descendants ruled the north and came to be worshipped in error. It sets the whole work inside a Christian account of how idolatry arose.
Gylfaginning, "the tricking of Gylfi", is the mythological narrative. A Swedish king comes to the hall of the Aesir and questions three figures on thrones about the origin and end of the world. Their answers run from the void of Ginnungagap and the killing of the giant Ymir through the making of humans, the world tree Yggdrasil, the halls of the gods, the binding of Fenrir and Loki, the death of Baldr, told at length and with genuine literary skill, and Ragnarok and the renewed world. The frame closes by revealing that the hall and the three questioners were an illusion.
Skaldskaparmal, "the language of poetry", is the technical core and the longest part. It catalogues kennings, the compressed metaphorical substitutions that skaldic verse runs on, gold as Sif's hair, poetry as Odin's drink, the sea as Ymir's blood, and explains each by giving the myth that licenses it, quoting hundreds of verses from named earlier poets. Several stories survive only here, embedded as explanations, including the theft of Idunn's apples and the origin of the mead of poetry.
Hattatal, "the enumeration of metres", is a poem of Snorri's own composition in praise of King Hakon and Earl Skuli, running through something over a hundred verse forms with commentary, and demonstrating each metre by being written in it.