As a curtain speech, it has just occurred to me that while the three books collectively are called The Lord of the Rings, the actual Lord of the Rings is Sauron, who barely makes an appearance at all. We see or feel his presence as a glowing eye of terrible awareness, through the power of the ancient undead kings he has enslaved, and through the massive threat of the armies he has assembled. (Compare, for example, how much screen time Darth Vader gets, to demonstrate how scary he is.)
Here, though, the story of the books named for Sauron is of the resistance to his will. We only learn his history through hints in these books that lead to the details written and published in other works (including the appendices in The Return of the King).
Interesting that Tolkien has left Sauron something of a blank, so that his menace taps into our own imaginations and deep fears. Who'd have thought that Oxford don Professor T. would use Hemingway's famous "iceberg" theory to such powerful effect?
If you haven't read The Hobbit and The Lord of the Rings, you are missing a great reading experience. It's fun to skim along on the surface, but the more you notice, the more you see. Tolkien was a genius. His work is a monument to history and imagination and adventure tales, but it includes and embodies some extremely modern stuff, as well (the emphasis on the story within the story, and the characters' awareness of their participation in the stories is an early, old-fashioned example of metafiction).
If you have any inclination toward heroic literature, the Middle Ages, Arthurian legends, quest novels, and/or the fantasy genre, give this one a try. Your personal Canon isn't complete without it.