Categories and keywords tell Amazon where your book belongs and help the right readers find it. They do not rank you, and no choice here replaces a good cover, a clear description and a well-edited book. But a careful choice costs nothing and a careless one wastes a free chance to be found. Here is a sensible way to approach both.
What each one does
Categories place your book in the shelves a reader browses. Keywords are the phrases a reader might type into the search bar. One is about where you sit, the other is about what people ask for. They work together, so choose them together.
Neither is a trick. Amazon's own rules say what is allowed, and they change, so read the current KDP help pages before you publish.
Choosing categories
Look at three to five books that are close to yours: same genre, similar tone, similar readers. See which categories they appear in. Then pick the shelves where your reader would really look, not the broadest or most flattering one.
A specific category is usually more useful than a crowded general one, because a book in a precise shelf is easier for the right reader to notice. You can revisit your choice later, so it is not a final commitment.
Choosing keywords
Think like a reader. What would someone type when they want a book like yours? Phrases about the genre, the setting, the situation, the kind of character or the problem the book solves tend to work better than single vague words.
Use the search bar itself: start typing a phrase and see what Amazon suggests. Those suggestions show what people actually search for.
- Use phrases a reader would really type, not just single words.
- Describe the book accurately; do not use terms that mislead readers.
- Do not use other authors' names or trademarks as keywords.
- Do not repeat words already in your title and subtitle.
- Skip words like free or bestselling that you cannot back up.
What to avoid
Keyword stuffing, misleading categories and borrowed famous names may look clever, but they attract the wrong readers, produce poor reviews and can put your listing at risk. A reader who feels misled does not come back.
No agency or tool can honestly promise that a keyword will put you at the top. Be wary of anyone who does.
Review after launch
After a few weeks, look at what is actually happening: which searches bring readers, and which shelves they come from. Replace phrases that are not working with ones suggested by what you see.
If you want help setting up a listing correctly from the start, Marlowe's Amazon KDP publishing service covers the details, categories and keywords included.