This document defines and describes several types of information systems: Transaction Processing Systems (TPS) which process routine transactions; Office Automation Systems (OAS) which help with tasks like document creation; Knowledge Work Systems (KWS) which help knowledge workers complete cognitive tasks; Decision Support Systems (DSS) which help with decision making; Executive Support Systems (ESS) which provide analytics for executives; and Group Decision Support Systems (GDSS) which help groups collaborate on decision making. Examples are provided for some systems.