Is ISBN same for both, paperback and hardcover editions of the book?

and is ISBN assigned only once to the book or every time the different publisher decides to publish the book?|||The paperback and hardcover have different ISBNs.|||There is usually two numbers issued. One for paperback and another for hardbound. However, sometimes the same ISBN number is used for both. Another thing worth noting is, if a book is updated from one year to the next it could have the same ISBN.|||Books tend to have multiple ISBN numbers to keep track of different versions like paperback, hardcover, different cover, but thee only number that are different are usually the last two or three digits. The rest is the same because essentially its the same book|||each book has one ISBN