The UPSC exam is structured in four main stages: the Preliminary Examination, the Mains Examination, an optional Interview, and finally the Medical Examination. The Preliminary stage is a qualifying exam consisting of multiple-choice questions testing general studies and aptitude. Candidates who pass proceed to the Mains, which includes nine written papers assessing detailed knowledge. The final stage, the interview, focuses on a candidate's personality and suitability for civil services. Together, these stages ensure a comprehensive evaluation of aspirants' capabilities and readiness.