on The Book Designer:
You learn something new every day! In this case, I recently had to revise my understanding of how Amazon handles keywords.
I’ve talked about keywords before; they’re an essential piece of metadata that determines how easy it is for the right reader to find your book. They are in many ways the key to discoverability. It is best to think of them, not as single words, but as search phrases — that is to say, groups of words that your ideal reader is likely to search for.
Put a different way, what question is your ideal reader likely to ask to which your book is the answer?