Dewey Decimal System Explained: A Simple Way to Make the Library's Catalog Work for You

I worked in a library for about 5 years. In that time, I helped a lot of patrons who seemed baffled by the intricacies of the Dewey Decimal system-the most common way to organize nonfiction in public libraries. Trying to understand the whole thing at once can be daunting. But the key is, you don't need to understand it all, just the parts that are right for you.

Here's a brief overview of how the system works and how it can work for you.

How it works:

1. Every book has a number, called the "call number," that tells you where it is.

2. That number is between 000 and 900 and may have several decimal places.

3. The hundreds represent broad topics, the tens represent subtopics, the ones represent really subtopics, and the decimal places represent sub sub sub topics.

4. For example, a book on American cooking (as long as it's marketed as "American" and not "vegetarian" or "BBQ" for example) would have the call number 641.5973. The 600s are sometimes called technology or applied science, but I think that doesn't really capture what they're about-there's books on medicine, space travel, gardening, pets, cooking, business, and more in the 600s.

640s are generally called "Home Ec." or "family living." So they've got things like frugal living, cooking, sewing (for practical uses, not for art), child-raising, and the like. 641 is specifically cooking. And .5973 is where they put books on American cooking. "973" is a designation for America, so the .5973 actually makes some sense.

Wow that was complicated, right? It's ok, you don't have to know all those little details, because you can make the system work for you.

Making it work for you:

Next time you get a book from a section you frequently use, look at its Dewey number. I check out a lot of books on personal finance. The number for that is 332.024. Now I know that most PF books will be in that section. If I go to another library, I know right where to look. Use the library's database, card catalog, or reference librarian to get you started.