What makes India a federal country?

The salient features of federalism in India are as given below:
(i)Two-three levels of government: In the beginning, the Constitution provided for a two-tier system of government i,e., the Union or National government and the State government. Later, a third-tier of federalism was added in the form of Panchayats and Municipalities. These tiers enjoy separate jurisdietion.
(ii) Division of powers: The constitution provides division of powers between the union/ central government and the state governments. There are three Lists – Union List (defense, Foreign affairs, banking, communication and currency), State List (Police, trade,-commerce, agriculture and irrigation), and Concurrent List (education, forest, trade, unions, marriage, adoption and succession) The residuary powers have been vested with the central government.
(iii) Amendment to the constitution: Sharing of powers or division of powers is basic to the structure of the Constitution and cannot be changed easily. The Parliament has to pass an Amendment in both the Houses with at least two-thirds majority. Then it has to be ratified by the legislatures of at least half of the total States.
(iv) Independent courts and interpretation of the Constitution: In case of any dispute about the division of powers, the High Courts and the state governments can raise their resources by levying taxes in order to carry on the government and the responsibilities assigned to each of them.