The number of information systems that are accessible through the Internet is constantly increasing. Information systems on those systems are getting varied and occupy more space, too. Up until a few years ago, only textual information sources were accessible via computer networks, whereas today multimedia information sources containing graphics, sound, pictures, and animation are also accessible over the Internet. Geographic information systems, electronic libraries, film and TV archives can he given as examples of multimedia information sources, We point out that information retrieval should he seen as an integral component of the computer networks, and technological, economic, and legal problems in this field should he solved. We end up ...