The book's story is set in the world of Tolkien's legendarium, making use of its richly detailled background, among them history and languages. It is a sequel to The Hobbit, or There and Back Again.
It has become one of the most well-known and best-loved stories of all time. Its popularity has caused Tolkien to be generally considered the "Father of Modern Fantasy"; its story, prose, and depth have secured its place in today's literature.
Writing and publication
The Lord of the Rings was begun as a sequel to the previously published The Hobbit. The Hobbit was originally not conceived as part of the Middle-earth legendarium, but when Tolkien began writing the sequel, he made it part of his previously-existing legendarium. Writing, re-writing and editing took him over a decade.
Upon publication the publisher insisted on splitting the book, much to Tolkien's dismay. Tolkien had internally structured the book into six sections named Book I-VI, and Appendices. The Lord of the Rings was then split into three Parts named The Fellowship of the Ring, The Two Towers, and The Return of the King, each containing two Books. Each part was then published in a separate volume, the first two in 1954, and the last in 1955. This has given rise to the mistaken notion of the The Lord of the Rings being a trilogy or a series, although it is neither. It has since also been published in a single volume, as intended by Tolkien.
The Fellowship of the Ring
An old Bilbo Baggins leaves the Shire, leaving his home and possessions to Frodo Baggins, along with the ring he found on his adventure sixty years previously. Eighteen years later, the wizard Gandalf visits Frodo and tells him about the true history of the ring: It is the One Ring created by the dark lord Sauron, in which he had put part of his own life and power upon its creation. Sauron had been defeated millenia before, but could not die fully as part of him remained alive in the Ring. He has since been regaining power and is searching for the Ring: should he regain it, he would become incredibly powerful again, which would surely mean the end of the free peoples of Middle-earth. Also, the Ring has a will on its own, and is a malevolent influence on its bearer, corrupting him over time; Frodo has been save from it so far by never having used it, and by virtue of being a hobbit, who seem to be less prone to its evil influence. Frodo sets out from the Shire with several friends to take the One Ring to Rivendell, where its further fate shall be decided.
In Rivendell the "Fellowship of the Ring" is formed, consisting of the ring-bearer Frodo and eight companions, with the goal of taking the One Ring to Mordor and destroy it in the volcano Mount Doom, where the Ring was made, and which is the only place it can be unmade. At the Falls of Rauros the Fellowship is separated: Frodo decided to go on alone, but is joined by Sam.
The Two Towers
The hobbits Merry and Pippin are kidnapped by Saruman's orcs, and the remaining members of the Fellowship decide to follow and rescue them. They get embroiled in the affairs of the human kingdom of Rohan and its fight against Saruman. In the end Saruman is defeated.
Frodo and Sam have separated from the Fellowship, journeying on towards Mordor. They meet Gollum, a previous bearer of the Ring and thoroughly corrupted by it; they take him with them as their guide, as he knows the way. In the mountains bordering Mordor he betrays them, and Frodo is captured by orcs.
The Return of the King
Sauron' armies attack and besiege the capital of the human realm Gondor, the city Minas Tirith, but are defeated in the end, aided by the arrival of armies from Rohan and Southern Gondor. Gondor and Rohan sent out a joined army to the Black Gate of Mordor to provide a distraction to Sauron and his armies, hopeful that their true plan of the Ring's destruction might go unnoticed.
Sam rescues Frodo from the orcs, and both continue on through Mordor. When they finally reach Mount Doom, Frodo has fallen completely under the power of the Ring and is unable to destroy it, putting it on instead. Gollum appears and fights him, biting off his finger with the Ring. Deliriously happy and triumphant upon having regained the Ring, Gollum missteps and falls into the volcano with the Ring, destroying it. The destruction of the One Ring kills Sauron, and his armies at the Black Gate scatter and are easily defeated by the armies of Gondor and Rohan. The hobbits return home, where they have to thwart the occupation of the Shire by Saruman's men. In the end, Frodo leaves with Bilbo and Gandalf on an Elven ship for the West, hoping to find peace and healing for his hurts and wounded spirit.