The Dewey Decimal system is used in more than 200,000 libraries throughout the world and it has been translated into 35 languages. Using numbers and letters, the system coordinates materials on the same subject and on related subjects to make items easier to find on the shelves. All knowledge is divided into ten main classes, which are listed below.
These ten classes each have ten divisions. These divisions are further divided--and then further divided, with each division becoming more specific. The more numbers, the more specific the subject. The decimal place is used to make the number even more specific. Click here for a detailed summary of each number.