A comptroller or controller; also financial controller) is a person who supervises accounting and financial reporting within an organization. A controller is an accountant in a business who oversees accounting and the implementation and monitoring of internal controls. In the United States, the United Kingdom, and Canada, a controller or financial controller is a senior position within most companies, often reporting to a Chief Financial Officer.

Control is one of the managerial functions like planning, organizing, staffing and directing. It is an important function because it helps to check the errors and to take the corrective action so that deviation from standards are minimized and stated goals of the organization are achieved in desired manner.
According to modern concepts, control is a foreseeing action whereas earlier concept of control was used only when errors were detected. Control in management means setting standards, measuring actual performance and taking corrective action. Thus, control comprises these three main activities.
 

Management accounting is concerned with the provisions and use of accounting information to managers within organizations, to provide them with the basis to make informed business decisions that will allow them to be better equipped in their management and control functions.
In contrast to financial accountancy information, management accounting information is:
• usually confidential and used by management, instead of publicly reported;
• forward-looking, instead of historical;
• pragmatically computed using extensive management information systems and internal controls, instead of complying with accounting standards.

This is because of the different emphasis: management accounting information is used within an organization, typically for decision-making. According to the Chartered Institute of Management Accountants (CIMA), Management Accounting is "the process of identification, measurement, accumulation, analysis, preparation, interpretation and communication of information used by management to plan, evaluate and control within an entity and to assure appropriate use of and accountability for its Resource (economics)resources. Management accounting also comprises the preparation of financial reports for non management groups such as shareholder's, creditor's, regulatory agencies and tax authorities" (CIMA Official Terminology)

The American Institute of Certified Public Accountants(AICPA) states that management accounting as practice extends to the following three areas:
• Strategic Management—Advancing the role of the management accountant as a strategic partner in the organization.
• Performance Management—Developing the practice of business decision-making and managing the performance of the organization.
• Risk Management—Contributing to frameworks and practices for identifying, measuring, managing and reporting risks to the achievement of the objectives of the organization.

The Institute of Certified Management Accountants(ICMA), state "A management accountant applies his or her professional knowledge and skill in the preparation and presentation of financial and other decision oriented information in such a way as to assist management in the formulation of policies and in the planning and control of the operation of the undertaking. Management Accountants therefore are seen as the "value-creators" amongst the accountants. They are much more interested in forward looking and taking decisions that will affect the future of the organization, than in the historical recording and compliance (scorekeeping) aspects of the profession. Management accounting knowledge and experience can therefore be obtained from varied fields and functions within an organization, such as information management, treasury, efficiency auditing, marketing, valuation, pricing, logistics, etc."