In a general sense, the term information system (IS) refers to a system of persons, data records and activities that process the data and information in an organization, and it includes the organization's manual and automated processes. In a narrow sense, the term information system (or computer-based information system) refers to the specific application software that is used to store data records in a computer system and automates some of the information-processing activities of the organization. Computer-based information systems are in the field of information technology. The discipline of Business process modelling describes the business processes supported by information systems.

Source : http://en.wikipedia.org/wiki/Information_system