Henry Mintzberg identified five types of organizational structures that help define how organizations operate. These structures are the simple structure, machine bureaucracy, professional bureaucracy, divisional structure, and adhocracy. Each type varies in terms of hierarchy, specialization, and the degree of formalization, influencing how decisions are made and tasks are coordinated. The simple structure is characterized by a flat hierarchy and minimal formalization, often found in small startups. In contrast, the machine bureaucracy relies on standardized processes and a clear chain of command, typical in large organizations. The professional bureaucracy emphasizes skilled professionals, while the divisional structure organizes teams around products or markets. Lastly, the adhocracy promotes flexibility and innovation, adapting quickly to changes.