Foundational concepts in public administration relevant to UPSC include bureaucracy, governance, and policy making. Understanding the roles of executive, legislative, and judicial branches is crucial, as is knowledge of public policies and their impacts on society. Familiarity with concepts like transparency, accountability, and administrative reforms is essential. Additionally, aspirants should study the working of institutions and theories of organisation to grasp how they operate within the context of governance. This knowledge base is key to answering questions effectively and understanding practical implications.