The significance of the Preliminary examination in the UPSC Civil Services process lies in its role as a screening test. It determines which candidates progress to the Mains examination, thereby acting as a filter for hundreds of thousands of applicants. This stage assesses candidates on their general awareness, current affairs, and comprehension skills through objective questions. It serves as a critical first hurdle, emphasizing the need for a strong foundation in General Studies and time management. Success in the Prelims is essential as it sets the stage for further stages of the recruitment process.