BISAC stands for Book Industry Subject and Category, a standardized set of categories developed by the BISG (Book Industry Study Group). The BISG is a U.S. trade association with a relatively simple mission: to simplify and streamline logistics for publishers and booksellers. Many arms of the book industry have adopted BISG policies and standards.
BISAC Subject Headings are actually pretty straightforward. The full list for 2014 is available here. They’re organized simply: a main category, then a subcategory. Here are the current headings:
Those are our major categories. Within those, there are subcategories. Let’s say we’ve written a young adult novel that centers on a divorce within a family. We might choose “JUVENILE FICTION” as a main category. Within that, we’re presented with a very large list of subheadings (look for yourself!) Those have a number in addition to descriptors. A few examples within that category include:
JUV031010 JUVENILE FICTION / Performing Arts / Circus
JUV033210 JUVENILE FICTION / Religious / Christian / Science Fiction
JUV039100 JUVENILE FICTION / Social Issues / Peer Pressure
JUV064000 JUVENILE FICTION / Time Travel
You can see how these work—they allow both customers and booksellers to look for books that tackle specific themes or exhibit certain features (that they’re about animals, maybe, or that they’re set in Europe.) The categories are quite flexible. For our hypothetical book, we might choose: JUV013020 JUVENILE FICTION / Family / Marriage & Divorce.
Of course, our book probably fits into multiple categories. If you’re publishing a new book, it’s worth fully perusing the BISAC Subject Headings and picking out several that might work for your book.
Amazon bases its browsing categories on BISAC subjects. Most first-time authors encounter the need for BISAC codes when they’re using a Print on Demand service like CreateSpace and are asked for one. CreateSpace allows authors to choose one BISAC subject—during the publishing process, it will give you a clickable list to choose from.
Similarly, Kindle Direct Publishing allows authors to choose two browsing categories to list their book in. These too are based on BISAC categories (though not exactly), so when you’re choosing your categories, they’ll be similar to these BISAC codes. When choosing Amazon browsing categories, it’s generally advisable to get as specific as possible, as smaller categories have less competition for sales rankings. (Fiction might have millions of books listed, for example, but Fiction -> Fantasy -> Urban may only have a few dozen.)
The usefulness of BISAC codes extend beyond Amazon, of course. Since this method of categorizing books is an industry standard, you may be asked for headings that apply to your book by any number of publishing services, online retailers, or printers.