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 (selected by the shareholders). In these countries, the CEO 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.