Henri Fayol proposed 14 principles of management that are still relevant today. The principles include division of work, authority, discipline, unity of command, unity of direction, and subordination of individual interests. Fayol also defined management as having five key elements: prevoyance (planning), organizing, commanding, coordinating, and controlling. Peter Drucker expanded on management principles by introducing management by objectives, which focuses managers on achieving clear objectives in key areas like marketing, innovation, human organization, finances, and productivity. Objectives should be specific, measurable, achievable, realistic, and time-related.