The subjects covered in the UPSC Civil Services Preliminary Examination include General Studies (GS) Paper I, which encompasses topics like history, geography, polity, economy, environment, and current affairs. Additionally, GS Paper II (also known as the CSAT) assesses candidates' comprehension, logical reasoning, analytical ability, and decision-making skills. These subjects are designed to evaluate a candidate's holistic understanding of various domains that are essential for effective governance and public service, ensuring that aspirants possess a well-rounded knowledge base before advancing to the next stages of the examination.