Udyog Aadhaar Registration was the previous MSME registration system in India, allowing entrepreneurs to obtain a unique Udyog Aadhaar Number (UAN) for micro, small, and medium enterprises. Registration was online, paperless, and required basic business details along with Aadhaar authentication. This system enabled businesses to access government subsidies, loans, and support programs. Although Udyog Aadhaar has been replaced by Udyam Registration, existing entrepreneurs can still update, verify, or migrate their old UAN records to the new system. The registration process ensures formal recognition, compliance with MSME regulations, and eligibility for financial and operational benefits. Udyog Aadhaar registration laid the foundation for digital recognition of MSMEs and continues to support historic data access for legacy businesses.