Information system are used by organizations to collect, process and distribute the information. These systems uses communication technology and information to make use of it. Main components of information systems are technology, information, procedures, management and users. Information systems are designed according to the need of the organizations. These are categorized into many types, each having different functionality and uses. Major types of information system are described here. Transaction processing system Decision support system Executive information system Management information system Enterprise resource planning and Expert systems. Online Analytical Processing (OLAP) Transaction Processing System The main purpose of Transaction Processing System