This is an epic, high fantasy series by J.R.R. Tolkien. The series takes place in the fictional world of Middle Earth, a land filled with magic, dragons, and other fantasy creatures which Tolkien helped define and develop.
The series was inspired by old myths and fairytales of England and Scandinavia, especially Beowulf.
Mythical creatures include elves, dwarves, orcs, goblins, and hobbits - little people who live a life in peace, mostly by farming.
The Hobbit is considered more of a children's adventure book, whereas The Lord of the Rings is much more serious in tone.
Besides these two works, Tolkien also wrote many others based in Middle Earth, which he didn't live to see published. These include The Silmarillion, Unfinished Tales, The History of Middle Earth Series, and The Children of Hurin, all of which were edited by Ronald Tolkien's son Christopher.
The Lord of the Rings was originally meant as one volume, to be paired with the Silmarillion, but publishers decided to sell it as three, partly to do with paper shortages during WWII, each consisting of two books - six total. It's a bit confusing, but The Lord of the Rings is considered one novel with six books in three volumes - and yet it's not a trilogy.
In this book, a young hobbit named Bilbo agrees to join an adventure with a group of dwarves, to kill a dragon and reclaim their mountain home. They are led by a wizard, Gandalf the Grey, and Thorin Oakenshield, who would be king under the mountain. Along the way, Bilbo finds a strange gold ring that turns him invisible. Little does he know just what he's found and how dangerous it is.
The Lord of the Rings:
In this novel, Bilbo's nephew Frodo must take this ring of evil to Mount Doom, a volcano where it can be destroyed. This will in turn destroy Sauron, the dark lord who created the ring, and wanted to rule all of Middle Earth. The pinnacle of evil, his power was broken when he first lost the ring in battle, thousands of years ago. But, until it's destroyed, his will lives on, compelling orcs, ogres, and trolls to gather for war. Meanwhile, a fellowship of good races form to help Frodo, consisting of the ranger Aragorn, the elf prince Legolas, Gimli the Dwarf, and Boromir, son of the Steward of Gondor, as well as three of Frodo's hobbit friends: Samwise, Merry, and Pippin.
Many scholars have debated over hidden meanings and symbolism in The Lord of the Rings. Many note similarities between events in the novel with that of WWII. For example, in a land where a dark force prepares for war, the good nations of the earth remain weak and divided. The powerful elves (Americans) feel safely isolated across a great sea, and would not sacrifice their loved ones for a war in the old world. The forces of darkness, forming to the south and east are united, with Sauron (Hitler) manipulating a puppet to do his bidding - Saruman (Mussolini). The result is a world war that reaches every corner of Middle Earth, and ending with the total defeat of an evil empire.
While these similarities can't be denied, Tolkien came up with his ideas decades before WWII, and vehemently denied the connection or use of his stories as an allegory for real world political events. He thought it would be an insult both to real world tragedies, and the creativity of his works and the substantial mythology he had created.
Tolkien did see Hitler as an evil force, not unlike Sauron. Specifically, he took issue with Hitler's racist theories regarding northern, white, Aryan races being superior to smaller, browner people living elsewhere in the world. The Lord of the Rings was a kind of celebration of Nordic, Scandinavian culture and tradition, and the last thing Tolkien wanted was his life's work being compared to Nazi propaganda.
Tolkien didn't see German people as the enemy, but merely victims of the same propaganda and industry that killed so many others, which was also a main theme in the book - how industry can ruin the landscape, dull men's hearts, and create terrible weapons. He reacted to the bombing of Dresden and other German targets saying:
"We were supposed to have reached a stage of civilization in which it might still be necessary to execute a criminal, but not to gloat, or to hang his wife and child by him while the orc-crowd hooted. The destruction of Germany, be it 100 times merited, is one of the most appalling world-catastrophes. Well, well,—you and I can do nothing about it. And that [should] be a measure of the amount of guilt that can justly be assumed to attach to any member of a country who is not a member of its actual Government. Well the first War of the Machines seems to be drawing to its final inconclusive chapter—leaving, alas, everyone the poorer, many bereaved or maimed and millions dead, and only one thing triumphant: the Machines"
Tolkien did agree that his book contained some Christian references, such as a parallel between the scenes of Mount Doom and The Lord's Prayer. But Tolkien objected to openly connecting fantasy with The Bible, and strongly objected to C.S. Lewis doing so in his Chronicles of Narnia.
"The Lord of the Rings is of course a fundamentally religious and Catholic work; unconsciously so at first, but consciously in the revision. That is why I have not put in, or have cut out, practically all references to anything like 'religion', to cults or practices, in the imaginary world. For the religious element is absorbed into the story and the symbolism."
The strongest parallels between The Lord of the Rings and Christianity come from its concept of evil and the temptation of sin, as symbolized by the ring. It appears to grant freedom, letting the wearer do as he pleases, but ultimately turns you into the servant of the fallen angel. As in the Bible, Sauron was once a good and wise wizard (something like an angel), before being tempted himself to evil.