This New York Times e-single features reviews of the 10 books, fiction and nonfiction, that the Times selected as the 10 Best Books of 2011. Choosing our 10 Best Books of the Year was not an arbitrary process, but neither was it a scientific one. How could it be, when the editors here, like all readers, respond subjectively to any work of fiction or nonfiction? The one guideline for the 10 was that they had to have been reviewed in our pages sometime in the past 12 months. Our 100 Notable Books of the Year were narrowed down to this final list, which contains a contingent of four first novels, Stephen King's 52nd novel (by our count), and nonfiction books that are models of their various forms - biography, memoir, history, argument and scientific analysis.