The exact balance of power between the central and the state governments varies from one federation to another. There are two kinds or two ways in which federations have been formed : (i) The first example is where independent states come together on their own to form a bigger unit. They, by pooling sovereignty and retaining identity, can increase their security. This type of coming together federations include USA, Switzerland and Australia. In this first category, all the constitutent states usually have equal powers and are strong vis-a-vis the federal government. (ii) The second category is where a large country decides to divide its powers between the constitutent states and the national government. India, Spain and Belgium are examples of this kind of holding together federations. In this second category, the central government is more powerful vis-a-vis the states. Very often different constituted units of the federation have unequal powers. Some units may be granted special powers.