The three phases of the UPSC Civil Services Examination consist of the Preliminary Examination, Main Examination, and the Interview (or Personality Test). The Preliminary Examination serves as a screening test with objective-type questions, evaluating general studies and aptitude. The Main Examination comprises descriptive-type papers, focusing extensively on various subjects including essay writing and general studies. Finally, the Interview assesses the candidate's personality, analytical skills, and suitability for a civil service role. Together, these phases ensure a comprehensive evaluation of aspirants.