ONLINE PUBLIC ACCESS CATALOGUE (OPAC)
By late 1970s, libraries began to use computers for cataloguing purpose and the idea of making the catalogue of a library available to its users online began to be accepted and has been implemented in a number of libraries. This computerised online catalogue, which can he searched by the users directly for the retrieval of records without the assistance of a trained intermediary is commonly known as Online Public Access Catalgoue ((PAC).