Traditionally Libraries kept records of their resources on cards, usually known as the card catalogue. Cards were sorted in author order, title order, and sometimes under subjects or keywords depending on the institution and were thus rather restrictive, having very few searchable terms or options for cross referencing. The first card catalogues are recorded as far back as 800AD in the House of Wisdom, a library in Baghdad. The first printed card catalogue appeared in 1595 at Leiden University.
With the advent of the computer, a much more flexible system of cataloguing became available. Computers as we know them have been around in one form or another since World War 2, but the first library that developed a computer based library catalogue was Ohio State University Library in 1975. Dallas Public Library was the first public library to move to a computer record of their catalogue in 1978. The 1980’s was a boom decade for OPAC (Online Public Access Catalogue) with nearly all public libraries in the Western World converting to computers both for their catalogue and also their database of borrowers.