Centralisation, or centralization (see spelling differences), is the process by which the activities of an organisation, particularly those regarding planning and decision-making, become concentrated within a particular location and/or group.
In political science, centralisation refers to the concentration of a government's power - both geographically and politically - into a centralised government.
In neuroscience, centralisation refers to the evolutionary trend of the nervous system to be partitioned into a central nervous system and peripheral nervous system.
In business studies, centralisation and decentralisation refer to where decisions are made in the chain of command.