This is an epic masterpiece. This is the cosmology and history of Middle-earth. It starts with the creation of the world by the god-like being, Iluvatar. From there He creates angelic beings called Valar and Maiar. These beings interact with each other, create things, and the story perpetually unfolds. We learn of the creation of Elves, of Men, of Dwarves, and lots of other entities. There is Fëanor and the creation of the Silmarils, wars fought, and much more. Then there's Melkor: the angelic being who turns bad and falls from grace. He remains the antagonist throughout the narrative. All of it sets the stage for The Lord of the Rings timeframe.
This was very new and different to me because my only Middle-earth exposure is the Lord of the Rings films and The Hobbit book. There are a lot of charters, places, and concepts that I was unfamiliar with: so I resorted to Youtube videos and Wikipedia to help me along the way.
Its a little minblowing to think J.R.R. Tolkien came up with all of this. I would recommend this to fans of LOTR, The Hobbit, and the whole Middle-earth scene.