One feature of a Unitary State is that it has a centralized system of government where all the powers are held by a single central government. The central government may choose to delegate powers to local or regional governments, but these powers are not guaranteed by the constitution and can be revoked at any time. This means that there is an absence of a constitutional division of power to the sub-national units. The size, economic development or heterogeneity of the population within the state may vary, but these factors are not necessarily defining characteristics of a Unitary State.