The Silmarillion is Tolkien’s posthumously published 1977 book about the mythology of Middle-earth.
Christopher Tolkien edited and arranged the material for publication after his father’s death. The book was published by George Allen & Unwin on 15 September 1977. It presents a mythic history extending from the creation of the world through the First Age and beyond.
Its central objects are the Silmarils, three jewels made by the Elf Fëanor. Their theft by Morgoth drives much of the First Age’s tragedy and connects stories involving Beren and Lúthien, Túrin Turambar, and the fall of Gondolin.
The Silmarillion is not a conventional sequel to The Lord of the Rings. It is a collection of legends, chronicles, and mythic accounts assembled from Tolkien’s extensive papers. The Children of Húrin and Unfinished Tales are separate posthumous publications.