How do those walk-through scanners in libraries know if you’re taking a book without borrowing it, especially if those books don’t have metal inserts or anything like that?

Question

How does the library borrowing system work? and how come even if there is no obvious metal insert in the book those gates still know when and when not to beep if the book has or hasn’t been borrowed?

In: Technology

Answer 1

The most well-known anti-theft device for books is a tape of magnetic metal strip. The tapes are applied between the spine and the binding of a book (for hard covers) or deep inside in between some pages (for paperbacks). It’s called **tattle-tape**.