Seamless synchronization across devices. You can start a book on your Android phone and pick up where you left off on a tablet or web browser.
Instant borrowing of not just books, but also movies, music, and comics with no "holds" queue. 2. Personal Cataloging Apps (Home Library) Library Book App Android
Widely considered the gold standard for ease of use. Seamless synchronization across devices
These apps are designed to help you keep track of the physical books you already own. Libby, the library app - App Store - Apple but also movies