Centralization refers to an organizational structure where decision-making power is held at the top management level and subordinates follow senior instructions. Centralization is suitable for small organizations with limited resources that cannot delegate effectively. Factors like nature, size, tasks, delegation ability, and employee efficiency can determine whether an organization centralizes. Centralization allows for cost efficiency, better command and control, uniform actions, and focus on vision, but it can slow operations, reduce adaptability, and overburden top management.