Good management and a good understanding of an organisation mean, first and foremost, mastery of the management tools that enable the manager to exercise direct control over the operations carried out. On the other hand, as soon as the company grows in size and management becomes complex, requiring the division of functions, the manager resorts to the delegation of tasks, responsibilities and skills through decentralised responsibility centres. In this way, the manager must implement tools that enable him to gather the information needed to make decisions and to ensure that these decisions are followed and respected. Control is exercised at every level of the organisation, i.e. at strategic level to ensure strategic control, at line management level to ensure management control, and at operational centre level to ensure operational control.