How do you close an ibook?

To close an iBook, simply tap the "Back" button in the upper-left corner if you're in a specific chapter or section. Alternatively, you can swipe down from the top of the screen to access the menu and select "Close." If you're using a Mac, you can click the red "X" button in the upper-left corner of the iBooks window. This will exit the book and return you to your library.