The Lord of the Rings is a book written by J. R. R. Tolkien. It was first published in 1954. It is split in three parts (or volumes), which are named The Fellowship of the Ring, The Two Towers, and The Return of the King. It was written after The Hobbit.
The Lord of the Rings takes place in Tolkien's fictional world, called Middle-earth. Middle-earth has its own geography, several different races and peoples (elves, dwarves, humans, hobbits, ents), their languages, and a history that is thousands of years old.
The plot of The Lord of the Rings is about the war of the peoples of the fantasy world Middle-earth against a dark lord known as "Sauron." At the same time they try to destroy a ring which would give Sauron a lot of power if he got it, but the only place to destroy the ring is deep into Sauron's land Mordor.
The Lord of the Rings has also been made into films, the most well-known is the film trilogy directed by Peter Jackson.