Effective control depends on communicating information to management. By issuing performance reports. the controller advises other managers of activities requiring corrective action. These reports emphasize deviations from a predetermined plan, following the principle of management by exception. The principle of management by exception is a belief that managers should be provided with information that directs their attention to activities that require corrective action. The concept is premised on the belief that managers do not have time to review every action of every subordinate nor to consult with each subordinate prior to each action. This is not to say that mmanagers' main task is correcting problems or "putting out fires," but simply that maagers need not take actons in the many ares where the work is proceeding as olanned. Using the accounting system and other systems, the controller provides information for planning a company's future and for controlling its activities. This information goes far beyond the basic financial statements. Inestors, govenment agencies, and other external parties also receive information by which management's effectiveness may be judged. This information is usually communicated to external users by means of Quarterly and annual reports that include financial statements but lack the depth of explanatory detail available to internal decisin makers.