An out-of-print book is a book that is no longer being published. The term can apply to specific editions of more popular works, which may then go in and out of print repeatedly, or to the sole printed edition of a work, which is not picked up again by any future publishers for reprint. Most works that have ever been published are out of print at any given time, while certain highly popular books, such as the Bible, are always "in print". Less popular out of print books are often rare and may be difficult to acquire unless scanned or electronic copies of the books are available. With the advent of book scanning, and print-on-demand technology, fewer and fewer works are now considered truly out of print.