Adapting any book to the big screen is a difficult undertaking. Inevitably, things are going to get cut, changed or moved around.
When you've got the task of adapting something as epic as Tolkien's the Lord of the Rings you're gonna have to change a lot. The combined series contains over 480,000 words spread across three books; trying to condense that down into three movies was going to require some clever reshuffling.
Peter Jackson and his team took a task deemed impossible, even by Tolkien himself, and managed to pull it off with spectacular results. Although many much loved chapters and characters were omitted, the changes he made (for the most part) were necessary to bring Tolkien's world to life.
In some places those changes deviated heavily from the original writing, but unless you're some kind of purist, they only benefitted the flow of the narrative and the arc of the characters.
These are the biggest but smartest changes Jackson and his team made to the Lord of the Rings.
10. Condensing The Early Timeline
Early on in the writing process, Peter Jackson and his team decided to significantly reduce the opening chapters of the Fellowship of the Ring. One of the major changes involved shorting the timeline between Bilbo's birthday and Frodo setting out for Rivendell.
In Tolkien's book, seventeen years pass between Bilbo leaving the Ring to Frodo, and Gandalf returning to inform the hobbit of its true origin. During this time Gandalf was uncovering the secrets of the Ring, while Frodo was doing literally nothing... , it would have made for some dull viewing.
This had the knock of effect of changing the age of Frodo, however. By the time he set out, Frodo was 51 years old, and in the books this worked; he's portrayed as a wise and well-informed hobbit, in significant contrast to his fellows. But it was necessary to portray him as a more naive and innocent figure in the films.
He essentially serves as the audience's eyes and ears in Middle Earth. It was far easier to empathise with his struggle, when we felt as though he knew as little about the wider world as we did.