This book aims at helping the reader develop a clear understanding of text retrieval systems, including its nature and characteristics; steps to be followed in developing a text retrieval system; software packages available for the purpose; guidelines for choosing an appropriate software, and so on. To make the text suitable for all kinds of readers, chapters and the basics of database technology, database management, and file structures appropriate for text retrieval systems have been provided. This book also discusses the major features of Library Management Systems (LMSs), the software packages used for automating library housekeeping operations. The trend is to developing systems which can provide the actual information sought by the use rather than reference to the information sources or part of the text where the search term appears. Such systems apply expert systems and natural language processing techniques, and are called knowledge-based systems (KBSs). This book describes features of these systems and mentions some of the applications of KBSs in library and information activities.