A good example of centralization is the establishment of the Common Core State Standards Initiative in the United States. Centralization is a process by which planning and decision-making of an organization are concentrated in one group or location. Centralization has advantages and disadvantages, and it doesn't always refer to politics.
In a centralized system, the central government makes policies and hands them down to local authorities for execution. Some believe decentralization tends to improve efficiency in the public sector, as citizens have more opportunities for decision making. Opponents to decentralization argue that giving too much power to subnational units may hurt national interests.