All organisations need information systems in order to function effectively. Every information system, whether for a one-man business, a parish council, a multinational corporation or the government offices of a large industrial nation, is made up of a number of components. The common denominator of the class of descriptive information is that it is very often highly formalised and therefore lends itself to application by computer. Descriptive information attempts to replace the real world of objects, of rules, and of events by a set of symbols which map the real world on a one-to-one basis. Qualifying and qualitative information used to moderate descriptive information from the formal system. An information system is thus a social system which uses information technology. The object of good systems design must be to develop systems which enable an organisation to utilise its resources more effectively and at the same time improve the quality of work of those who work for the organisation.