The entire story consists of several books, but the main LOTR is a trilogy, starting with The Fellowship of the Ring, and in sequence, The Two Towers, and finally The Return of the King. To glean the most from this series, start with the story that was the inspiration for LOTR, The Hobbit.
Cannot give enough praise to Rob Inglis. His narration, voicing of unique characters, AND singing the beautiful poetry of Tolkein is outstanding. Hobbits, elves, and the like sing quite a bit, in case you didn’t know! I can state that at least for me, the audiobook versions MUST be better than the written words.
These stories are deep into the SCI-FI fantasy genre, strictly for the young and the young at heart. Divorce your mind from reality completely and enjoy the adventures.