To appear in the UPSC examinations, candidates must meet certain eligibility criteria. They should possess a bachelor's degree from a recognized university, irrespective of the discipline. Additionally, candidates must be within the specified age limits, which typically range from 21 to 32 years, depending on their category (general or reserved). The aspirants must also meet criteria related to the number of attempts allowed, which varies based on categories. Meeting these eligibility requirements is essential for candidates to successfully register for the examination.