The National Book Award is an annual award in which only books published in the United State in the year of the award are eligible. Nominations are accepted only from publishers although panel chairs are allowed to request a book from a publisher.
There are four categories: Fiction, Nonfiction, Poetry, and Young People’s Literature. Each category has a panel of five judges who set their own criteria. The judges, new each year, are selected by previous winners and judges and the National Book Foundation. They are “chosen for their literary sensibilities and their expertise in a particular genre.” (from the National Book Award website)