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.
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 Middle-earth against a dark lord (who is the 'Lord of the Rings' of the title). At the same time they try to destroy a ring which would give the dark lord a lot of power if he got it, but the only place to destroy the ring is deep into the territory of the enemy.
The Lord of the Rings has also been made into Three films, the most well-known is the film trilogy directed by Peter Jackson.