Before getting down information system, it is better that we know the meaning of a system. System is a group of element that relate each other and operate together to reach a purpose and target. It means a system is not a set of structured element spasmodically, but a group of elements that integrated for the same purpose to reach a target or a mark. 

Generally,  model of a system consist of input, processor and output. It needs more simple because a system possibly has some inputs and output. Input system is all things that come into system that would be processed. Processor is a part that make a change or transform an input becomes useful output, for example summarizes data, does calculation, and sorts data. Output is a result of process e.g. information, suggestion, report. 

Information system according to Burch and Strater in his book “ Information System: Theory and Practice” is defined as a group of functions that join formally and systematically: ( a) executes operational transaction data processing, ( b) yields information to support management in executing planning activity, controlling, and decision making, ( c) yields various reports for external importance of organization.

Based on above definition, information system is a production system that process raw material to end user custom product. In an information system development, as a raw material is data, then an end product is information, while the consumer is a member of organization or related to the organization