It is estimated that Amazon has at least 50% of the print book market, and around 67% of the eBook market. Most authors realize the importance of having their books for sale on Amazon, but what they underestimate is the untapped markets outside of Amazon. This includes independent bookstores, libraries, museums, and other retail outlets. Per book marketing expert and New Shelves Books Executive Director Keri-Rae Barnum, it's critical that authors reach these other booksellers to maximize their sales. One of the best ways to increase a book's distribution is to upload it to IngramSpark. IngramSpark is a print-on-demand channel that is partnered with the sales arm, Ingram Wholesale. When books are uploaded to IngramSpark, they can be distributed through Ingram Wholesale, which has access to all types of booksellers. These are two different service providers that each get paid separately.