The Open Library, as it's called, allows users to borrow digital copies of books through a controlled digital lending system. This means they maintain a "one copy, one user" model - for each physical book they own, they can lend out one digital copy at a time.

Borrowers can access books through a web browser or using various e-reader apps. The books are available in different formats, including PDF and ePub, and are protected by DRM (Digital Rights Management) to ensure they can only be accessed during the loan period, which typically ranges from a few hours up to 14 days.