Third Person (Omniscient)
The book's narrator is mostly invisible to us, meaning we don't notice him or her very much as we read. There's so much action and dialogue that it's very easy to get lost in the story. Still, occasionally the narrator drops a term of endearment, like "our little party of travelers" (8.1), that reminds us that he or she exists, while also demonstrating genuine affection for the characters.
Every now and again—but not too often—the narrator provides special insight into the characters. Toto is a dog, so he can't talk (even in Oz!). But the narrator gives us a window into the little animal's heart: "Toto did not really care whether he was in Kansas or the Land of Oz, so long as Dorothy was with him; but he knew the little girl was unhappy, and that made him unhappy too" (12.71). The narrator also tells us when characters' internal feelings don't match up with their external behavior, like when the Scarecrow went to the Wizard's throne room. "The Scarecrow, who had expected to see the great Head Dorothy had told him of, was much astonished; but he answered her bravely" (11.69). These insights generally make us feel more sympathetic toward the characters; in other words, they make us care more.
Finally, the narrator occasionally makes a comment that hints at mysteries beyond the boundaries of the story. When the people of the Emerald City are proud for being the only city ruled by a stuffed man (the Scarecrow), the narrator tells us, "So far as they knew, they were quite right" (18.4). By even hinting that there could be another city, somewhere, ruled by a different stuffed man, the narrator subtly creates a sense of wonder and awe.