Scribd puts me in mind of the circulating library. Early in the 20th century, many people consumed fiction from a circulating library - simply another name for a private library. Users were charged a fee for the privilege of borrowing books from the library. Instead of buying one book, the customer paid an annual subscription and could borrow books for a set time. Typically, the subscription enabled the user to borrow just one book at a time. For a higher subscription, the customer could borrow more books at once.