This document outlines the Five Laws of Library Science as enunciated by Dr. S.R. Ranganathan in 1928. It summarizes each of the five laws: 1) Books are for use, 2) Every reader his/her book, 3) Every book its reader, 4) Save the time of the reader, 5) Library is a growing organism. For each law, it describes the principle and implications for library organization, management, and services. The five laws constitute the basic philosophy of library science and provide guidance for all library activities and practices.