This book provides readers with an engaging explanation of the Aleksandrov problem, giving readers an overview of the process of solving Aleksandrov-Rassias problems, which are still actively studied by many mathematicians, and familiarizing readers with the details of the proof process. In addition, effort has been put into writing this book so that readers can easily understand the content, saving readers the trouble of having to search the literature on their own. In fact, this book logically and kindly introduces the basic theories of related fields.