(i) A federation refers to a political structure in which there are two sets of governments i.e. one for the whole country and governments in each of the federal units (called Provinces or States). There is a distribution of powers between the Federal government (also known as Union or Central Government) and the State Governments. Federal governments are preferred in countries having large size and heterogeneous population. 

(ii) The main features of a federation are 

• Dual set of governments i.e., Union government and State governments. 
• Division of power between the two sets of governments for e.g., in India, jurisdiction is distributed between the Union (Centre) and States on the basis of Union, State and Concurrent list (as stated in Seventh Schedule of the Constitution) 
• A written constitution to enable a clear distribution of government powers. 
• Independent judiciary to resolve center-state or state-state disputes. 

(iii) Federation may be performed by two processes 

• Small political units ‘come together to establish a single unit for e. g., thirteen colonies came together to fight for independence from British rule and the US federation came into being. This is called centripetal process. 
• States are created by the union government for e.g., in India, states were reorganized on the basis of language and other regional aspirations. This is the centrifugal process.

(iv) India has been described as ‘quasi-federation’ or a ‘federation with an unitary spirit’ as the division of powers favors the central government for e.g. it has full control over the Union list as well as over residuary subjects. It’s laws have precedence even in case of the subjects in Concurrent list.