This document provides comprehensive Frequently Asked Questions (FAQs) regarding the Unique Document Identification Number (UDIN) system, as issued by The Institute of Chartered Accountants of India (ICAI). It covers the purpose, generation, and application of UDINs for various certifications, audits, and attestation functions. The FAQs are designed to assist Chartered Accountants in practice and other stakeholders in understanding and utilising the UDIN system effectively.