KDP Select is an optional program for eBooks published through Amazon. When you enroll, Amazon gets the exclusive right to sell your eBook for 90 days. This means you won’t be able to sell the digital version of your book on other platforms such as Apple Books or Google Play, or even on your own website during that 90 day period. However, you’ll still be able to sell printed copies (paperbacks and hardcovers) wherever you want.
After the 90 days, you can choose to remain in the program or opt-out.
The main downside to using KDP Select is that your eBook can ONLY be sold through Amazon for 90 days. You will have to remove the eBook from your own website as well as from any other platforms like Apple or Google during that time. For any authors who already have decent readership on those platforms, this option might be too limiting.
KDP Select is especially helpful for new authors or any author trying to build up a fan-base. The exposure through Kindle Unlimited and the ability to run promotions can help get your book noticed where it might not otherwise show up. However, if you would rather have high flexibility in where you sell your eBook, the exclusivity deal may not be for you.
Ultimately, you can test KDP Select with one book and see how it works for you. If it does in fact increase your readership, why not keep it. If not, you can always try other platforms for that eBook after the 90 days are up.