This document discusses the historical development of reference service in libraries. It traces how universal education in the 19th century and the establishment of public libraries led to the emergence of reference service. As literacy increased and libraries provided reading materials, librarians began assisting patrons who knew how to read but not how to use libraries. Samuel Green first outlined the concept of reference service in 1876. Reference service aims to teach users research skills and help them find information to answer their questions. It has evolved with changing technologies and patron demographics.