One of the first things to consider when reviewing book formats is narrative perspective. At its simplest, there are two kinds of narrative perspectives, first and third person. First person is told from the point of view of one character by which the the reader witnesses the actions of the story. Third person is not told by a particular character in the story but is rather told from an objective view. There are three ways to approach third-person storytelling. The first is with omniscient third person, which offers a view of everything in the story. Next is limited third person, which only offers information from a few perspectives. Last is unobtrusive, which shows all of the actions but not all of the character's thoughts.
The next thing to consider with book formats is fiction versus nonfiction. A fiction book is one in which the characters are entirely created, including the situations and actions that occur. However, nonfiction can based on actual events. A nonfiction book does not have to be about oneself; it can be based on real-life situations or historical events as well. Sometimes the two formats blur into one, such as when real-life occurrences are told through a writer's imagined dialogue of the event.
Another aspect of book formatting to consider is the timeline of your plot and how you would like the actions of your book to take place. In a linear plot, the events of your book play out from start to finish, one right after another in the exact order that they take place. However, nonlinear plots are becoming increasingly popular. These plots can start at the end and work their way backwards or can even depict multiple perspectives from various characters that may or may not have any correlation.
One last thing to consider with book format is the genre in which you will be writing. Most simply, your book will either be a tragedy or a comedy. Breaking down the tragedy genre, you could write a romantic tragedy, a domestic tragedy or even a revenge tragedy, among others. Comedies can be broken down into satire, farce, romantic or black comedy, which centers the comedic events around something that is not normally funny, such as a funeral or a war. The genre of your book affects the dialogue, the plot and the character types, among other things.