Authority control is as old as the catalogues. The need for it grows proportionally according to the variety and extent of a catalogue. Strict authority control directly impacts the quality of a catalogue, its clearness and practical use. Growing automation of bibliographic data bases and building union and shared catalogues have brought about new concepts of authority control although this was not
unknown to editors and users of classical bibliographic registers and catalogues. Authority files are the tool of authority control, they are often very extensive and exist especially in three fields: names, titles (serial publications) and key-words. Formation and maintenance of any single catalogue needs elementary authority control, but shared cataloguing demands a very strict one as an indispensable imperative. Authority control can be defined as a process of assuring oneness of any information chosen for a call point in a public catalogue. Authority files are the basis of a national system of bibliographic control. There is no doubt that in the future these systems will be linked also on the international level
