The core subjects in the UPSC Mains exam encompass a variety of disciplines crucial for prospective civil servants. These include General Studies papers that cover Indian heritage, geography, polity, economy, environment, and current affairs. Furthermore, candidates are required to choose one optional subject from a diverse list, which can range from sociology and political science to anthropology and geography. Language proficiency is also assessed through mandatory papers in English and an Indian language. The comprehensive nature of these subjects aims to equip aspirants with a robust understanding of the diverse challenges faced in governance and administration.