The value of library can be discussed and evaluated from various angles. The value and impact of libraries are divided into categories of social, cultural, educational, and economic. This book systematically describes the value of library, including the concept, characteristics, and evaluation indicators of the library's social, cultural, educational, and economic value. In Chapter 1, which is the starting point of this book, the 1) concept of value and impact, 2) characteristics of value, 3) domain of value, 4) classification of evaluation method, and 5) value of library that have been studied in various academic fields are introduced.