The updates were revealed by CEO Tim Cook during the iPad mini launch Tuesday and are already available to download from the App Store.
The revamped iBooks 3 app features a new "continuous rolling" reading option, which means if users flick the screen with their fingers, words will progress as they do when scrolling up and down a web page.
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iBooks is now better integrated with iCloud, Cook explained, meaning every title customers have purchased now resides on their bookshelf.
Users can download titles by tapping the cover as they already can with previously purchased apps, music and movies.
Easier sharing and more languages
New sharing options were also introduced, allowing users to post passages from books to Facebook and Twitter, while the app now supports over 40 languages, including vertical text in Chinese.
"The pages move from left to right just as you'd expect... if you're Japanese," quipped Cook during the unveiling.
The company said it now has 1.5 million books available to download from the store, while 400 million titles have now been downloaded by users in just over two years since the launch.
Textbook updates also easier
The iBooks Author refresh makes it easier for publishers to create multi-touch digital textbooks, bringing new templates, custom fonts and rendered mathematical expressions and formulas.
Better still, publishers can now push textbook updates directly to the user without the need to re-download the title, which is great for continually changing school curriculums.
The iBooks Author update is also available now and remains free to download.