The latest trend in eBook publishing is highly popular and gaining steam. Authors have been supplying custom dictionaries with their eBooks to help their readers. These new dictionaries are tailored for the subject matter contained within the book and function as a kind of index for the book itself. While this idea is nothing new in the non-fiction world, it is more groundbreaking for fiction eBooks. These dictionaries are proving to be quite popular with readers, especially.

Most of these dictionaries are rich media enabled to allow authors to add media, images and more to elaborate on their points and ideas. These are particularly useful for detailed fantasy and science fiction stories that have plots set in alternate universes or realities. Indie authors have been making use of these dictionaries in large numbers. By allowing authors to define and explain their own worlds and ideas, readers are given a more clear idea of the setting and more.

These features have been in use by nonfiction authors already, especially in technological and scientific areas where easy reference to complex content is always helpful. With the growing trend in the fiction arena now too, readers will be expecting more features with their fiction books as well as their nonfiction selections.