Amazon's search algorithm reads your title, subtitle, description, and author name, not just your seven hidden backend keyword fields, which means repeating a word you've already used in your title inside your backend keywords wastes space without adding any new reach. Understanding what's already indexed is the first step to using your limited 350 characters of backend keyword space efficiently.
This is part of the Complete Guide to Amazon KDP Keywords and Categories.
When a shopper searches Amazon, the algorithm checks your book's entire metadata package for a match, not just the hidden keyword fields:
Because all of these are indexed together, a word appearing anywhere in this set makes your book eligible to surface for a search containing that word. Repeating it in another field doesn't multiply your reach; it just uses space that could have gone toward a different search term entirely.
Since your title and subtitle are already searchable, don't spend backend keyword space on words already appearing there. If your title is The Last Lighthouse Keeper, you don't need "lighthouse" or "keeper" in your backend fields; that ground is already covered. Use your limited 350 characters instead on terms that aren't already represented anywhere else in your metadata: setting, character type, tone, trope, and audience terms your title and description don't already convey.
The same logic applies to your series name, if you're publishing a series. Amazon indexes the series name automatically from the Series field you fill in during setup, so using a backend keyword slot on your series title is generally wasted space; readers searching the series name will find your book through that field regardless.
While a compelling title is primarily about hooking a reader who's already looking at your book, it also carries search weight. A subtitle that includes a genuinely searchable phrase (not stuffed with keywords, but naturally descriptive) can do double duty: informing the reader and contributing to search matching. This is especially relevant for nonfiction, where subtitles often explicitly describe the book's content and audience in ways that overlap naturally with reader search terms.
Your book's description exists primarily to persuade a reader who's already looking at your page to buy, and that persuasive job should always come first; don't sacrifice a compelling description for the sake of keyword stuffing. But because the description is also indexed, writing it in language that naturally includes genre, trope, and audience terms (without sounding robotic or repetitive) can support your discoverability alongside your backend keywords, rather than working against it.
Need Help With Your Book's Metadata?
Entrada Publishing can help you think through your title, description, and keywords as a coordinated package.
No. Your title is already indexed for search, so repeating those words in your backend keyword fields wastes space that could go toward new search terms.
Yes. Amazon's algorithm considers your description alongside your title, subtitle, author name, and backend keywords when matching searches.
No. Amazon indexes your series name automatically from the Series field you complete during setup, so a backend keyword slot spent on it is generally wasted.
Search terms and angles not already covered by your title, subtitle, author name, series name, or description: setting, character type, tone, trope, and audience-specific language.