Henry Fayol developed 14 principles of management in 1916 based on his experience in the mining industry. Some key principles included division of labor, where workers specialize in certain tasks to promote efficiency; authority and responsibility, where a manager must have authority over subordinates; discipline, where workers adhere to company policies and priorities; unity of command, where each employee reports to one supervisor; and subordination of individual interests to the overall interests of the company. Over the next 20 years, these principles were discussed and expanded on by American authors and helped form the basis of modern management theory.