According to Article 1 of the Indian Constitution, the territories of India can be classified into the three following categories:

• The territories of the States
• Union Territories
• The territories that may be acquired by the Government of India at any time. 

At present, there are 28 states and 8 union territories and no acquired territories. 

Further Reading:

• Union Territories 
• States Reorganisation Act, 1956
• Difference between State and Union Territory