The word system is derived from the Greek word “system” which means a organized relationship among the following unit or component. "A system is an orderly grouping of interdependent components linked together according to a plan to achieve a specific goal". 

Office automation refers to the application of computer and communication technology to office functions. Office automation systems are meant to improve the productivity of managers at various levels of management by providing secretarial assistance and better communication facilities.

Structure of MIS may be understood by looking at the physical components of the information system in an organization. The physical components of an organizational information system may be hardware, software, database, manual procedures and operating persons. A brief description of these components has been outlined in the following paragraphs: 

DSS is an information system application that helps in decision-making. DSS is used in planning and analyzing alternatives. DSS differs from most traditional information system in that each DSS is distinct from the other information system and is specifically made for managers.

A Business Expert System (BES) is a knowledge based information system, which is based on artificial intelligence. A Knowledge Based information system adds a knowledge base that uses its knowledge about a specific, complex application area to act as an expert.