The principle of dyarchy (or diarchy) in the context of Indian history refers to the division of governance between elected Indian ministers and British officials, as introduced by the Government of India Act of 1919. This framework categorized subjects into reserved and transferred subjects, where the former remained under British control while the latter were managed by Indian ministers, aiming to provide limited self-governance while maintaining colonial authority. Understanding dyarchy is crucial for the UPSC examination as it highlights the evolution of constitutional reforms in India and the complexities of colonial governance that shaped the nationalists' struggle for independence.