What is X-ray you ask? X-ray is a feature on Kindle touchscreen devices. If set up properly, the reader can press on a character’s name or a location, and a box will pop up with a brief description or even a Wikipedia page entry. This feature is especially helpful when you’re reading a series with many characters or a novel with a lot of world-building. However, the author or publisher must facilitate it.
I have done this with all of my books. As a reader, I use X-ray all the time. If you haven’t tried it out yet, I encourage you to do so. And I urge all authors/publishers to enable this feature. It will enhance the reader’s experience.