The document discusses four major theories of organizational structure and management: 1. Classical theory focuses on scientific management and principles like specialization and hierarchy. 2. Human relations theory emphasizes psychological and social factors, informal groups, and participation. 3. Contingency theory states there is no single best way to manage and various situational variables must be considered. 4. Systems theory views the organization as an open system that receives inputs, transforms them through internal processes, and provides outputs to the environment.