What are the main functions of a CEO??

A Chief Executive Officer (CEO) or chief executive is the highest-ranking corporate officer, administrator, corporate administrator, executive, or executive officer in charge of total management of a corporation, company, organization, or agency. In internal communication and press releases, many companies capitalise the term and those of other high positions even when they are not proper nouns, in other words, even when they are not used in combination with the company name or as titles before a person's name.
In closely held corporations, it is general business practice that the chief executive officer is also the chairperson (or chair) of the board of directors. Specifically, one person often shares the titles of chairperson and CEO while another person takes the presidency or may become chief operating officer (COO). However, the term president is from the U.S. whereas managing director (MD) is favored in the UK. Next in line is the executive vice president (U.S.) or executive director (UK). In publicly held corporations, the positions of CEO and chairperson can be separated, but this entails appropriate changes in corporate governance.

In some European Union countries, there are two separate boards; one executive board for the day-to-day business and one supervisory board for control purposes (elected by the shareholders). In these countries, the chief executive officer presides over the executive board and the chairman presides over the supervisory board, and these two roles will always be held by different people. This ensures a distinction between management by the executive board and governance by the supervisory board. This allows for clear lines of authority. The aim is to prevent a conflict of interest and too much power being concentrated in the hands of one person. There is a strong parallel here with the structure of governments, which tend to separate the political cabinet from the management civil service.

In rare circumstances, an executive chairperson can be appointed, but this is either illegal or frowned upon by regulators in many jurisdictions.

In the United Kingdom many charities and government agencies are headed by a chief executive who is answerable to a board of trustees or board of directors. In the UK, the chair (of the board) in public companies is more senior than the chief executive. Most public companies now split the roles of chair and chief executive.

In France, a CEO/MD is known as the "PDG" (prÃ©sident directeur gÃ©nÃ©ral); in Sweden, the CEO/MD is known as "VD" (verkstÃ¤llande direktÃ¶r); in Spain, the usual name is "director general"; while in Italy, the position is called "AD" (which stands for amministratore delegato)
Reporting structure

Typically, a CEO has a cadre of subordinate executives, each of which has specific functional responsibilities. These direct reporting relationships most often include a chief financial officer, chief operating officer, chief marketing officer, chief information officer, and a director of human resources.

However, depending on the industry in which the company operates and/or the organizational structure the company has employed, various other functional areas may be highlighted through the CEO's direct span of control. Some of these less common monikers include the following: chief (business) development officer, chief knowledge officer, chief learning officer, chief strategy officer, chief risk officer, chief innovation process officer, chief credit officer, and chief creative officer.