Federalism is a system of government where power is divided between a central authority and various constituent units, each having its own jurisdiction. The Indian Constitution, while adopting a federal structure, exhibits a unique blend of federal and unitary features, often described as 'quasi-federal' or 'cooperative federalism'.

Key Federal Features:

1. Dual Polity: India has two levels of government – the Union government and the State governments – each with distinct powers and responsibilities.
2. Written Constitution: The Constitution is a comprehensive written document that clearly delineates the powers and functions of both the Union and State governments, ensuring clarity and preventing conflicts.
3. Division of Powers: The Seventh Schedule of the Constitution divides legislative powers into three lists: the Union List (exclusive to Parliament), the State List (exclusive to State Legislatures), and the Concurrent List (both can legislate, with Union law prevailing in case of conflict).
4. Supremacy of the Constitution: The Constitution is the supreme law of the land, and all laws enacted by the Union and State governments must conform to its provisions.
5. Independent Judiciary: An independent judiciary, headed by the Supreme Court, acts as the interpreter and guardian of the Constitution, resolving disputes between the Union and States, and ensuring the supremacy of the Constitution.
6. Bicameralism: The Parliament consists of two houses: the Lok Sabha (representing the people) and the Rajya Sabha (representing the States), providing a platform for states to voice their concerns at the national level.

Key Unitary (Non-Federal) Features:

1. Strong Centre: The Union government holds more powers than the States. The Union List has more subjects, and Parliament has residuary powers. In the Concurrent List, Union law prevails.
2. Single Constitution: Unlike true federations (e.g., USA), India has a single constitution for both the Union and the States, except for Jammu & Kashmir (which had its own constitution until 2019).
3. Single Citizenship: All Indians possess a single citizenship, irrespective of their domicile, fostering national unity.
4. Integrated Judiciary: India has a unified and integrated judicial system, with the Supreme Court at the apex, unlike separate federal and state courts in some federations.
5. Appointment of Governors: The Governor of a State is appointed by the President and acts as a representative of the Union government, potentially influencing State administration.
6. Emergency Provisions: The Constitution provides for emergency powers (Articles 352, 356, 360) that can transform the federal system into a unitary one, giving the Union government overriding authority.
7. Flexibility of the Constitution: While difficult, parts of the Constitution can be amended by the Union Parliament alone, without State ratification, making it less rigid than some federal constitutions.
8. All-India Services: Services like IAS and IPS are recruited and controlled by the Union, but serve in the States, ensuring uniformity in administration.

In essence, Indian federalism is a pragmatic and adaptive system designed to maintain national unity while accommodating regional diversity. It is often characterized as 'federal in form but unitary in spirit' or a 'holding together' federation, where the emphasis is on cooperation between the Centre and States rather than strict separation.