The Lord of the Rings is heavily influenced by Tolkien's interest in philology, [fairy tale]?s and Norse and Celtic mythology. Tolkien designed a complete mythology for his realm of Middle Earth, including genealogies of characters, languages, runes, calenders and histories.
The plot of the Lord of the Rings follows directly from his earlier book The Hobbit and more obliquely from the Silmarillion.
The hobbits of Tolkien's earlier tale become embroiled in great events that threaten their entire world, as Sauron, the embodiment of evil, attempts to regain the lost One Ring which will restore him to full potency.
There was an animated film made in 1978, directed by [Ralph Bakshi]?, based on The Lord of the Rings, which covered only the first volume. The intended sequels never appeared.
Three [live action film]?s, directed by [Peter Jackson]? have been filmed. "The Fellowship of the Ring" was released in December 2001. The Two Towers is scheduled to be released in December 2002 and The Return of the King is scheduled to be released in December 2003.
The [Encyclopedia of Arda] is a good source for further information.