The exclusive right of an author over his book is called copyright. Copyright is a legal concept that gives the creator of an original work, such as a book, the exclusive right to use, distribute, and profit from their work. This means that the author has the sole right to make copies of the book, distribute it, and create adaptations or derivative works. Copyright protection is automatic and does not require registration, although it is recommended to register with a national copyright office to have proof of ownership in case of any legal disputes. The purpose of copyright is to protect the intellectual property rights of authors and encourage creativity and innovation.