Best description of a unitary form of government?

A unitary government may be defined as on in which the powers are concentrated in the hands of a central government. There may be sub-divisions, but they are not free from the control of the central government. They are the creation or and derive their power from, the central government and as such are subordinate to the same in all respects. They are the mere agents of the central government. The best examples of the unitary government are that of Great Britain and France, Italy, Belgium, Japan and so on. For administrative convenience and other considerations the country may be divided into political divisions of different categories, but all authority control from the central government. These sub-divisions have no original existence of their own.