The Dewey Decimal Classification System is a method used to calssify books in the library. It was named after Melvil Dewey who developed it in 1876. The system uses numbers to organize the subjects of each nonfiction books and are divided into 10 main subject groups called categories. Each category is presented by a figure starting from 000 to 999. Each number presents a special topic. Books with the same number are placed in alphabetical order by the last name of the author. The first digit of a three digit number signifies the main class. Suppose you have 500, the 5 in signifies natural sciences and mathematics. The second digit signifies the division and the last digit signifies the sections.