Kindle X-rays. How do they work?

[[deleted user]]

I wonder how the x-ray on Kindle works. Does it choose important points from a book or does it choose based on reader interaction?

[Tomas, Wandering dreamer]

It needs to be set up by the author.

[Lynn]

Hi. What is Kindle X-Ray and how does it work. I just published my novel on Kindle Direct as both a paperback and as a kindle download. Is Kindle X-Ray offered by Kindle Direct?

[Tomas, Wandering dreamer]

Okay, this will be a bit harder to explain.
Copy-pasting from Amazon's help page:

X-Ray is a unique Kindle eBook feature that allows readers to learn more about a character, topic, event, place, or any other term, simply by pressing and holding on the word or phrase that interests them. X-Ray for Authors is a free Kindle Direct Publishing (KDP) tool that enables you, the author, to add your own descriptions or commentary that will show up when the reader engages the X-Ray feature. With X-Ray for Authors, you can add new X-Ray entries, edit existing ones, or enable X-Ray for a new book. At this time, X-Ray only supports eBooks published in English.

By default, for applicable words, it imports Wikipedia definition. For custom words (names, locations, creatures, ...) I presume it takes the first sentence where the word appears. You can replace that with your own custom description up to 1200 characters long (so, around a paragraph).

Amazon has a guide and a help article on that matter that should be easy to find in the KDP section.
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Edit:
If I understand it correctly, if you enable X-ray for your book, it'll go through some automated process that'll find the words it believes should be included, and find the excerpts. You can just flag all it finds as okay and do nothing else, or go one by one writing custom descriptions. You can remove some (if you don't want them to be shown by X-ray) or add those it did not catch.

[D.]

I set up x-ray for all my books. You go through everything the system highlights - names, places, etc. You can dismiss it, choose the Wikipedia definition, or write your own. When the reader reads your book, those words or phrases will be highlighted and they can choose to click on it for the definition or explanation. I think it's helpful for foreign readers or if you have a lot of characters and people might forget who everyone is.