In the folder named library. The open source reading app stores the cached books in a folder named library, because it is convenient for users to find and manage the books they have read. By storing the cached book files in this folder, users can easily access this folder through computers or other devices, find and back up the books they have read, and avoid the loss of books due to the failure or accidental deletion of their mobile phones. At the same time, it also helps users to transfer books synchronously between multiple devices, which improves the reading experience and convenience, so it is placed in a folder named library.