An information system (IS) is any combination of information technology and activities that support operations, management, and decision making. In a very broad sense, the term information system is frequently used to refer to the interaction between people, processes, data, and technology. In this sense, the term is used to refer not only to the information and communication technology (ICT) that an organization uses, but also to the way in which people interact with this technology in support of business processes.

Some make a clear distinction between information systems, computer systems, and business processes. Information systems typically include an ICT component but are not purely concerned with ICT, focusing instead on the end use of information technology. Information systems are also different from business processes. Information systems help to control the performance of business processes.

As such, information systems inter-relate with data systems on the one hand and activity systems on the other. An information system is a form of communication system in which data represent and are processed as a form of social memory. An information system can also be considered a semi-formal language which supports human decision making and action.

Information systems are the primary focus of study for the information systems discipline and for organizational informatics.

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