The personal interview is crucial in the UPSC selection process as it offers assessors insight into candidates' personality traits, confidence, and communication skills. It evaluates candidates on parameters like leadership, analytical abilities, and general awareness. The interview also allows candidates to elaborate on their academic background and experiences, ensuring a holistic assessment beyond theoretical knowledge. It plays a significant role in deciding the final merit list and helps the panel gauge a candidate's suitability for a career in the civil services.