The Silmarillion was published posthumously in 1977 from J.R.R. Tolkien’s writings about the history of Middle-earth.
Tolkien died in 1973, leaving a large and complex body of mythological material in different versions and stages of completion. His son Christopher Tolkien edited these writings into a publishable volume, with assistance from the fantasy author Guy Gavriel Kay. The book appeared four years after Tolkien’s death.
The Silmarillion begins with a creation account and continues through the history of the Elves, the First Age, and later events connected with Númenor and the Rings of Power. It is more mythic and compressed in style than The Hobbit or The Lord of the Rings.
It is often described as a single novel, but that is misleading. The book is a compilation of related legends, histories, poems, and genealogical material. Unfinished Tales, published later, contains additional narratives and commentary from Tolkien’s papers.