The constitution declared India as the Union of States.
The Constitution originally provided for a two-tier system of government, the Union Government or what we call the Central Government, representing the Union of India and the State government.
Later the third tier of federalism was added in the form of Panchayats and municipalities.
The Constitution contains three lists:
Union Lists: It includes subjects of national importance such as defense of the country, foreign affairs, banking, communications and currency.
State Lists: It contains subjects of States and local importance such as police, trade, commerce, agriculture and irrigation.
Concurrent Lists: It includes subjects of common interest to both the Union Governments, such as education, forest, trade unions, marriage, adoption and succession.