The acknowledgments in The Graveyard Book mention an "enormous debt" to Rudyard Kipling’s The Jungle Book. What does Gaiman mean by this?
The entire book is sort of a re-telling of The Jungle Book (hence the analogous name, The Graveyard Book) as a gothic urban fantasy.
From the very beginning, when Bod is brutally separated from his family and has to get acceptance from a council in order to be fostered/adopted into a new living arrangement, it follows the general outline of The Jungle Book. There is a silky, smooth teacher and also a furry, rougher teacher, there are many mini-vignettes (such as the kidnapping — and means of escape — on the way to Ghûlheim) that model corresponding scenes in The Jungle Book, and also entities like the Sleer that have a clear analog in the original.
Once a reader has cottoned on, it's quite enjoyable to read the two and compare them, to see Gaiman's rendition of/homage to what he clearly respects as a masterwork.