Udyam is the registration of a business under MSME (Micro Small Medium Enterprises).www.udyamregistration.gov.in is the official portal to register a new MSME or to re-register already registered EM – II (Entrepreneurs Memorandum Part - II) or UAM (UdyogAadhaar Memorandum).  The Ministry of Micro Small Medium Enterprises maintains this portal. 
Micro Enterprise
An enterprise whose investment in Plant, Machinery and Equipments does not exceeds One Crore and turnover does not exceeds Five Crores is a Micro Enterprise. 
