Imagine you have hundreds of great books, books you love and want to
share. How would you keep track of them? How would you make
it easy for you and your friends to find something fun to read?
You might start with a list of the books - in a library, this is called
a "catalog". Today, libraries use computers to
create their catalog. Using a computer makes it easy to search the
listing of books.
You would also probably want to group books, keeping books on similar
topics together. That way, it will be easy to look on a shelve and
find all the books that cover a topic. Libraries do this too -
nonfiction books are grouped together by subject. Fiction books
are grouped together alphabetically by their author.
The system that libraries use to organize books on shelves was invented
by Melvil Dewey, who lived from 1851 to 1931. Using the
Dewey Decimal System, each book is assigned a three-digit number
based on what it is about - think of it as a code for that subject.
A book's Dewey number is also called its "call number".
A digit is one number, 0 through 9. For example, the number 629
has 3 digits - the first one is a 6, the second is a 2, and the third is
a 9. The first digit of a three-digit Dewey number tells you what
main Dewey group a book belongs in.
The Dewey Categories are:
000 General Knowledge. Encyclopedias, general
reference works, computers, newspapers, magazines
100 Philosophy and Psychology. Optical
illusions, brain research, question and answer books
200 Religion and Mythology. Bible stories,
religions of the world, Greek myths
300 Social Science and Folklore.
Communication, education, law, sociology, transportation,
etiquette, folklore and fairy tales
400 Language. Grammar books, sign language,
dictionaries, and picture books in many languages
500 Math and Science. Experiments,
mathematics, astronomy, chemistry, physics, geology, biology,
dinosaurs, books on specific animals
600 Medicine and Technology. Human body,
medicine, airplanes, space travel, cookbooks and domesticated
animals such as dogs, cats, horses
700 Arts and Recreation. Art, artists,
how-to-draw books, crafts, origami, music, joke and riddle
800 Literature. Poetry, plays and classic
900 Geography & History. History, geography
and travel, atlases, explorers, and biographies
To see examples of the subject areas and Dewey numbers that are popular
with kids, click HERE.
As you can see from our Dewey listing above, the main categories can
cover many different subject areas. The second digit in a book's
Dewey number subdivides the subject and tells you what a book is about.
This keeps books on the same subdivision together, making it easy to
look for books that are on the shelves.
The third digit provides even more information. It breaks the
subdivision down into even more groupings by subject. Additional
digits after the third digit, placed after a decimal point (.), narrow
the subject matter down even more.
Dewey numbers can be used to create very specific groups of books, all
about the same topic or subject. This is why you can look at the
nonfiction books on the shelves of a library and see that books on the
same subject are always kept together. What a great idea!
Each book has a label that shows the Dewey number and the first three
letters of the author's last name. This label is put on the
"spine" of the book - the part of a book you see when you look
at the shelves. The spine usually also has the title of the book
printed on it and the name of the author.
In libraries, nonfiction books are put on the shelves in the order of
their Dewey numbers. The numbers act as a code, telling you what
the book is about. The numbers keep books about the same topic
This makes it easy to look for and find books that you want to read.
If you know where to look for the Dewey number, finding books is simple
- when you know the Dewey number, you know where the book should be on
The Dewey numbers keep books on the same topic together. This
makes it easy to go into a library and look at books that are on the
shelves. Similar books are together. You can look at the
shelves containing the Dewey numbers for the subjects you are
interested. Finding books like this is called "browsing".
The Dewey number also makes life easier for librarians. When you
return a book, they can put it back on the shelves by looking at the
Dewey number and putting it back in order on the shelves.
Sometimes, libraries have books that are too big for their shelves,
these books are called "oversized books". Libraries
still assign them Dewey numbers, but put them in order on special
shelves that are large enough for these big books.
Fiction books can be placed in the Dewey Decimal System, in the 800's,
but most libraries have a special fiction section instead. Instead
of having a large section of fiction within the 800's, it is easier to
put fiction books together on shelves alphabetically by author.
Most libraries use the three letters FIC to show that a book is fiction.
Instead of giving it a number, libraries just use the first three
letters of the author's last name. For example, a fiction book
written by John Meyers would be assigned FIC MEY.
Even though this results in assigning a code that is all letters,
librarians still call this a "call number". Keeping
fiction books arranged alphabetically by author makes it easy to find
books. It also makes it easy to find more good books written by
your favorite authors.
So imagine you had hundreds of great books that you enjoy reading and
sharing. Using the Dewey Decimal System for nonfiction and
assigning each book a call number using a three-digit code would be a
great idea. For fiction books, you could create a call number
beginning with FIC, followed by the first three letters of the author's
This is what libraries do. If you had hundreds of good books,
wouldn't this system also make it easy for you to to organize and share