The two stages of the UPSC Civil Services Examination are the Preliminary Examination and the Main Examination. The Preliminary serves as a qualifying test with multiple-choice questions covering various subjects. Successful candidates then proceed to the Mains, which consists of written exams in descriptive format. The Mains evaluates a candidate's understanding and analytical abilities across several subjects, followed by an interview stage that assesses personality and suitability for civil services. Together, these stages evaluate both theoretical knowledge and practical skills.