CHAPTER ONE
INTRODUCTION
1.1    BACKGROUND OF THE STUDY
Information is a basic human need. It is needed virtually in all facets of human endeavor such as teaching, learning, business, decision making, education, travel etc. No modern society can function effectively within the intensive of information whether in print or non print format.
It is therefore pertinent to know how these information can be harness, retrieved and disseminated for use by the user or the society in a modern world. The different methods of information retrieval are therefore discussed in this write up with special interest on Onitsha divisional library.
The word information cannot be mentioned in isolation of human beings. Information has been described as the master resource, the chief raw material and the principle product of modern economics. Even before the modern world, the ancient world has been dealing with information gathering storage and retrieval which were done in an ancient ways where papyrus, clay tablets etc were used. Information can be seen as data that have been subjected to some logical processing or functions capable of answering a user’s query, be it recorded, summarized or simply collected that would help in decision making.
Information retrieval methods or systems came into beings as a means of ensuring that information generated and recorded do not get lost over time. Before knowledge became, individuals formed the repository of knowledge. With libraries, repository of knowledge began to change into recorded form. Nowadays the quantity of new information being generated is such that no individual can hope to cope with this information explosion and at the same time make them available to users. This led to the use of information retrieval with minimum cost in time, labour and money. Information retrieval method or system therefore is the process of searching some collections of documents in order to identify those documents in order to identify those documents which deals with a particular subject.
Reitz (2004) defines information retrieval (IR) as the process, methods and procedure used to selectively recall recorded information from a file of data. In libraries, searches is made typically for a know item or formation on a specific subject, and the five is usually a human readable catalogue or index, or index, or a computer-based information storage and retrieval system, such as an on-line catalogues and bibliography database. In the design of such systems, a balance must be attained between speed, accuracy, cost and effectiveness. Any system that is designed to facilitate the literature searching activity may legitimately be called an information retrieval system. The catalogue, Index and bibliography, abstract as well as computers is known as information retrieval systems (IRS)
In the library today, instead of the individual storing the knowledge in the brain and mind, we have the corporate store, the library, instead of the individual memory, we have the corporate memory. The library catalogues, bibliographies indexes and computers. These information retrieved systems (tools) contain the bibliographical details of documents such as the author, edition, call-number, publisher, place of publication, date etc. These details help the user to identify the current title, author of the document without which retrieval becomes impossible.