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How to Use the Dewey Decimal System

Updated on October 18, 2012

Dewey Decimal Numbers are used worldwide

No matter where you go, the numbers mean the same thing.
No matter where you go, the numbers mean the same thing. | Source

Learn How to Understand Those Little Numbers on the Spine

Welcome to your hometown library! I bet you are here to do some kind of research, aren't you? Are you writing a resume? Are you looking for a really terrific recipe for chicken cacciatore? Maybe your kid needs to do a history fair project? Are you trying to figure out what to feed your pet hamster? Or you are just aching to know all about Leonardo Da Vinci?

If you are looking to learn anything - how to do something, where to find something, how to understand or appreciate something, or even. well, what not to wear... if you are in a library, you are going to end up trying to use the Dewey Decimal System. You will find that your browsing experience will be much more efficient and effective if you understand what those little numbers mean. It's not random! It's actually a very elaborate and carefully constructed organization system that arranges all the world's knowledge into ten different categories. Those ten categories have sub-categories. The sub-categories have sub-sub-categories. And so on, until the number is finally precise enough to give you the exact book you need for the question of the day.

The Dewey Decimal System: it's the original search engine. So let's learn how to use it!

Melville Dewey... or was it Melvil Dui?
Melville Dewey... or was it Melvil Dui? | Source

Why is it called the Dewey Decimal System?

The Dewey Decimal System is named after its originator, Melville Dewey (1851 - 1931.) Dewey was an eccentric fellow, always looking for ways to make things simpler. For awhile there he was an advocate of removing all extraneous letters from words in the English language. During that period, he demanded that his colleagues refer to him as "Melvil Dui." Dewey was one of the Founding Fahers of libraries in America; he helped found the American Library Association, he edited Library Journal, and established the first library school in America at Columbia University. He was also apparently notoriously difficult to get along with and had a reputation as a womanizer. Hey, who knew America's most famous librarian could be so colorful?

The Dewey Decimal System Organizes Information

Melville Dewey, the guy who wanted to make everything simpler, decided that everything that exists in the world can be divided into ten basic categories:

  • 000 - General works
  • 100 - Philosophy and Psychology
  • 200 - Religion
  • 300 - Social Sciences
  • 400 - Language
  • 500 - Science and Mathematics
  • 600 - Applied Sciences
  • 700 - Arts and Recreation
  • 800 - Literature
  • 900 - History and Geography

From there, he divides knowledge further and further, and every time he decides we need an additional division of knowledge for greater precision, we get another number after the decimal point. For our purposes, we will look at 100 categories.


000 - General Works

For this category, Melville decided to include any books that contained information about a really wide variety of subjects. In the modern era, we have added one particular innovation that Dewey did not know about - computers. The 000s look like this:

000 - 009: Computers and the Internet: If only Dewey could have lived to see the day.

010 - 019: Bibliographies. Yep, we've got a whole set of numbers dedicated to books that are basically lists of other books

020 - 029: Library Science. He dedicated an entire array of numbers to his own profession.

030 - 039: Encyclopedias, Books of facts. This is where you put a collection of different kinds of information.

040 - 049: "Special Topics." This set of numbers is seldom used anymore.

050 - 059: Magazines, journals and serials. This set of numbers is also not often used in public libraries. Public libraries usually put magazines in their own area. However, books about magazines might go here.

060 - 069: Associations and organizations. Go here to find out where you belong.

070 - 079: News media, journalism, publishing. All the news that's fit to print.

080 - 089: Collections, in many different languages - This includes quotations, essays, and anecdotes about various things. It's basically a hodgepodge of stuff that didn't fit anywhere else. This could be said for much of the 000s. .

090 - 099: Manuscripts and rare books. This section is often covered with dust.


100 - Philosophy and Psychology

If it has to do with how people think, it's likely to be in the 100s. Of course, Dewey was very much a man of his time and place; notice the amount of space he allocated for Western and classical philosophical thought, and how much he dedicated to Eastern philosophy. One of the reasons why Dewey numbers sometimes get very long after the decimal is that Dewey didn't always leave enough space for cultures and ideas that were not closely connected to nineteenth century United States.

100 - 109: Philosophy (General works) So, what is philosophy, exactly? Why should I care? Who am I? Why am I here? Will this be on the exam?

110 - 119: Metaphysics What is my maker? Who sent me here? What is the universe? How does this all work? Does an exam exist, and how long is it?

120 - 129: Epistemology What do I know? How do I know it? Is what I know the same as what you know, and do you believe it will be on the exam?

130 - 139: Paranormal Never mind, I've just been abducted by a UFO. The spirits will tell me all, and if they don't know, I can ask the Loch Ness Monster on my way through the Bermuda Triangle.

140 - 149: Specific schools of philosophical thought - rationalism, existentialism, humanism, idealism, all the isms. This is what happens when philosophy gets a little more organized.

150 - 159: Psychology Why am I like this and how did I get this way? Is there any way to fix it?

160 - 169: Logic Elementary, my dear Watson. It's all a matter of deduction, reasoning and critical thinking.

170 - 179: Ethics But more importantly, what is the right thing to do?

180 - 189: Ancient, medieval and eastern philosophy. This is a crowded house. Aristotle, Socrates and Plato get to share a bunk with some zen masters, some yoga instructors, some Islamic philosophers and Confucius.

190 - 199 Modern Western philosophy. Meanwhile, Ayn Rand, John Dewey and David Hume are hanging out with John Stuart Mill. Only philosophers from modern America and Europe need apply.


200 - Religion

We have ten sets of numbers to examine people and their relationship with God. Once again, Dewey's organization scheme is a little bit biased here. Most of the numbers have to do with Christianity. Some of the decimal numbers in the 290s get VERY long to separate all the other sects.

200 - 209 : Religion Books that deal with religion in a very general manner.

210 - 219: Religious theory - Folks explain why they believe what they believe. Interestingly, this is where you are likely to find books about atheism and agnosticism.

220 - 229: The Bible - We've got ten numbers just to display the Christian Bible - Bible commentary, Bible concordances, Bible study guides, Bible trivia, . It's the B-I-B-L-E.

230 - 239: Christian theology - If the 210s discussed what people in general believe, this set of numbers analyzes what Christians believe.

240 - 249: Christian practices and customs - Here we will find books about how Christians go about practicing the beliefs we looked at in the 230s.

250 - 259: Christian pastoral practices - Here where to go if you want to know how Christian minsters do their jobs.

260 - 269: How the Christian church is organized - Christian places, sacraments, rites, missions, Christian associations and organizations

270 - 279: History of Christianity - How all of this stuff developed through the centuries, all over the world.

280 - 289: Christian denominations - Catholics and Protestants, Episcopalians and Baptists, Mormons and Jehovah's Witnesses, etc.

290 - 299: Comparative Religions - Everybody else. Really. Come here to find out about different kinds of world mythology, and then all the other major world religions - Hinduism, Buddhism, Judaism, Islam, with Paganism and Scientology bringing up the rear. Some day, they may need to rethink this. This place is so crowded some of it spills over into the philosophy section.


300 - Social Sciences

The 300s are about people, and how they get along with other people... and what can happen when they can't get along with other people.

300 - 309: Social Sciences - Sociology, anthropology, social behavior, social groups - basically anything that discusses how people live together in a community.

310 - 319: Statistics - Keeping a count of everything people do, all over the world.

320 - 329: Political Science - The government, the governed, and how they work it out - civil rights, the election process, the legislative process, and slavery

330 - 339: Economics - Resources of all kinds and how we use them. The science of figuring out how to pay the bills.

340 - 349: Law - What laws are, how to follow them, and the court systems for those who don't.

350 - 359: Public Administration - Central government, local government, the military forces, and war.

360 - 369: Social Services - Social problems and how to solve them. Poverty, counseling, volunteerism, charities, healthcare and health insurance, and crime.

370 - 379: Education - Education for all ages, from elementary through University, and government regulation of it.

380 - 389: Commerce, communication and transport - How we sell goods to people across the globe, let them know when to expect it, and somehow get it there.

390 - 399: Customs, etiquette, and folklore - How to behave, how to dress, and... fairy tales. This is also where you will find books about holidays.


400 - Languages

The 400s cover the Tower of Babel - all the different languages we use all over the world. You will find a lot of bilingual dictionaries in this area. If you want to learn a foreign language, this is where you will go.

400 - 409: Language - How languages developed and how they are used.

410 - 419: Linguistics - The alphabet, etymology, dictionaries, grammar, and words

420 - 429: The English Language - How to write it, how to use words correctly and how to get the grammar right.

430 - 439: The German Language - How to write it, how to use words correctly and how to get the grammar right.

440 - 449: The French Language - How to write it, how to ... you get the idea.

450 - 459: The Italian Language - How to write it, and so forth.

460 - 469: The Spanish Language - How to write it, etc... oh, look there, at the end - Portuguese in the 469s!

470 - 479: The Latin Language - Veni Vidi Lego - I came, I saw, I read books about ancient Latin.

480 - 89: The Greek Language - The language here is all Greek to me.

490 - 499 Other Languages - Sure, we can crowd Japanese, Swahili, Russian, Arabic, Hebrew, Chinese, and hieroglyphics together with Esperanto. There's plenty of room. Expect very long call numbers.


500 - Science

Here we have science as theory - discussions of how things work and how we can study and understand the forces that shape the universe around us. This is the science of Einstein and Isaac Newton.

500 - 509: Science - A basic introduction. Theory. scientific organizations, scientific dictionaries, journals, research, and natural history.

510 - 519: Mathematics - algebra, arithmetic, geometry, probability, and how to use all of it.

520 - 529: Astronomy - Here's the place where the stars really come out to shine - along with the planets, the galaxies, and quarks.

530 - 539: Physics - How everything works: How liquid flows, how gasses rise, how sounds vibrate, how gravity keeps everything from flying away.

540 - 549: Chemistry - All these things that exist in the universe: Mix it all up and see what you get. You will find the elemental table in here.

550 - 559: Earth science - Geology, hydrology, petrology. I think I felt the earth move.

560 - 569: Paleontology - Digging up the past. Here there be dinosaurs, and many other dead animals.

570 - 579: Life sciences - Going back to the present, we look at life and what causes it - biology, anthropology, evolution, microbiology, and how to collect it all.

580 - 589: Botany - All about plants and how they grow - but not how to grow them. We will cover that later.

590 - 599: Zoology - If the 560s covered animals that died long ago, here we have all the animals that exist now in nature - except for pets. They are elsewhere.


600 - Applied Sciences

The 500s were about studying the natural forces around us and how they work. The 600s are about how we use them - how we make things, how we take care of them, and how we manipulate the physical things around us to improve our standard of life. This is the science of Henry T. Ford and Thomas Edison.

600 - 609: Technology - A general overview of all the stuff we make, how we make it, and what it does for us.

610 - 619: Medicine - Just what the doctor ordered: anatomy, physiology, diseases, drugs, drug abuse, surgery, pregnancy, gynecology, and all the latest diet fads.

620 - 629: Engineering - You see that machine over there? How did we make it work? Through engineering! Military engineering, nautical engineering, civil engineering, railroad engineering, hydraulic engineering, municipal engineering... you can even find a book on how to build a toilet.

630 - 639: Agriculture - How to grow it, where to grow it, what to grow, what kind of fertilizer you need, and when to harvest it. This is also where you find all the books on farm animals and pets. Insects happen in here somewhere and then we all go fishing.

640 - 649: Home economics - And this is for all you housewives and househusbands out there: cookbooks, bartender's guides, books on how to run your house, sewing, fashion, parenting, and how to get that nagging stain out of the carpet.

650 - 659: Management - This is where you learn how to run your business. Resumes, Cover letters, management practices, accounting, and advertising are all found here.

660 - 669: Chemical Engineering - How we make chemicals for industry, chemicals to blow stuff up, and soft drinks. Learn the chemistry of food, ceramics, cleaning fluid, and metallurgy.

670 - 679: Manufacturing - Learn how we use metals of all kinds, lumber, leather, pulp for paper, and fabric.

680 - 689: Manufacturing, in more detail - This is the place for blacksmiths, household appliances, home furnishings, leather, fur, printing and clothing.

690 - 699: Building and construction - How to make a shelter, basically. How to do it, what materials to use. and how to install the lights, heat and air conditioning once the building is erected.


700 - Arts and Recreation

This is the section of the library where a bunch of veddy, veddy cultured books about ballet, fine arts, theater and photography are just sitting down to tea when the party is crashed by a bunch of tomes in football jerseys taking bets on the outcome of the Kentucky Derby before settling down for a game of poker.

700 - 709: The Arts: What is art? How do we define it? Where do we find it? Where can we go to observe it?

710 - 719: Civic and landscape art: Planning the landscape, planning the trafficways, water features, plants we use to make our landscapes pretty, and cemeteries.

720 - 729: Architecture: Designing buildings through the centuries, from temples and cathedrals to your own house.

730 - 739: Sculputure: Statues through the ages, made out of a whole bunch of different materials ranging from marble to trash.

740 - 749: Decorative Arts - Drawing, perspective, decorating your house, glass and furniture.

750 - 759: Painting - Painting techniques, including the use of color, symbolism, and different motifs.

760 - 769: Graphic Arts - Bluck printing, lithographs, metal engraving, etching, drypoint, prints.

770 - 779: Photography - How to take the picture, how to develop the picture, how to make it look 3D, how to digitize it, how to recreate it on a computer, and how to turn the whole thing into a video.

780 - 789: Music - Vocals and instruments, chamber music, sheet music, music theory. This section can place Beethoven, the Beatles and Marilyn Manson side by side.

790 - 799: Recreation - OK, enough with the hoity toity stuff. Let's get ready to rumble! We've got every kind of game, from darts and hopscotch to football and baseball, and then the bookies take bets on the horse races while another group of guys start playing blackjack.


800 - Literature

To be read, or not to be read... that is the question. In the 800s we find all kinds of literature, in all kinds of languages. Shakespeare's hanging out in this neighborhood with Langston Hughes and every other important poet you've ever heard of.

800 - 809: Literature, rhetoric and criticism - General works about literature, rhetoric, literary history and criticism.

810 - 819: American Literature - Literature written in the United States: poetry, drama, fiction, essays, speeches, letters, satire and humor and puzzles. Look for Thoreau, Walt Whitman, Emily Dickinson, and Robert Frost. Thank goodness they took the novels out and put them in alphabetical order in their own section, or this would be the longest section in the library.

820 - 829: English Literature - Literature written in Great Britain: poetry, drama, fiction, essays... you get the picture. Here you will find Shakespeare and everybody commenting on his work.

830 - 839: German Literature - Literature written in Germany: poetry, drama fic... yeah, we've done this before.

840 - 849: French Literature - Literature written in France: poetry, drama, fiction, and so forth.

850 - 859: Italian Literature - The pattern is becoming very clear. Looking for Dante's Inferno right about now...

860 - 869: Spanish and Portuguese Literature - All the same categories, now in Spanish. Has anybody seen a crazy guy fighting a windmill?

870 - 879: Latin Literature - Ovid, Virgil, Horace, Cicero. Bring your toga to the party.

880 -, 889: Greek Literature - Sophocles, Homer, and the face that launched a thousand shiips.

890 - 899: Literature from everywhere else - The great literary melting pot.

900 - History and Geography

The final section of the Dewey Decimal System is reserved for books about everything that ever happened, everywhere it ever happened, to anybody it ever happened to.

900 - 909: History and Geography - General works.

910 - 919: Geography and Travel - Come here to find out how to get where you are going, and what you can expect to see and experience when you get there. The original GPS.

920 - 929: Biography and genealogy - Remembering the important people of the past, or maybe just of your families' past.

930 - 939: History of the Ancient World - Where Ghengis Khan meets Cleopatra and Pericles. A different number for each country.

940 - 949: History of Europe - Europe through the centuries, from the Magna Carta and the Black Death through Napoleon, two world wars and the adoption of the euro.

950 - 959: History of Asia - China, Japan, Arabia, India, Iran and the Middle East.

960 - 969: History of Africa - Tunisia, Libya, Egypt, Sudan, Ethiopia, Morocco, Algeria; all the dark stories from the Dark Continent.

970 - 979: History of North America - From the Native Americans who walked here through the colonists who founded the modern nations we have today.

980 - 989: History of South America - Keep a look out for Simon Bolivar and Eva Peron.

990 - 999: History of Everywhere Else - If you get all the way to 999, the books will take you out of this world and into the possibilities of the universe.

So that's it - all the knowledge of the world broken up into ten categories, which have ten subcategories. The subcategories each have subcategories, and after that, they start splitting the numbers up into decimals for more and more precise distinctions of categories. Below you will find links to a few more detailed guides to Dewey. Now, of course, the next question is this: How do you find out what the call number for any given book is? Well, you use the catalog, and I've got a tutorial for that right here.

Now, go forth and seek knowledge at your local library!


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    • Written Up profile image

      Written Up 

      6 years ago from Oklahoma City, OK

      I found myself surprisingly drawn to this information. Very cool.

    • Rosie writes profile image

      Rosie writes 

      6 years ago from Virginia

      I love it! I am bookmarking your hub for future reference. It will be a fantastic resource. Nice job!

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      6 years ago from Las Vegas

      This is a complete reference hub, great information and is very helpful. I love it. Will bookmark this one for sure!


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