Even in the developing countries, the Web searching is fast catching the imagination of the young library readers to locate the desired information and this trend influenced adversely information search pattern on library systems like online catalogue. Nonetheless, the online catalogue still holds a significant place as a necessary tool to locate and access quality information, available in the print or electronic formats. In fact, readability is still considered easier through the printed documents. In this context, OPAC can function like a portal and be exploited to extend indefinitely for connecting to diverse resources, available in the library, of the interest to the users; besides playing a significant role as a comprehensive reference tool in the library. The present book examines all such and interconnecting issues by raising a pertinent question: How OPAC can function as a retrieval tool in the libraries for effective, efficient and easy access to library resources in face of advances made in the field of computer and communication technology, in general and search engine, in particular. Organized into seven chapters, the book comprehensively covers the theme. Designed especially for the researchers and the teachers in the discipline of library and information science is hoped to prove immensely beneficial for the working librarians, information professionals and system designers