Aadhaar is a unique Identification number issued by UIDAI to individuals for the purpose of establishing the unique identification of every single person. Aadhaar is actually a 12-digit number and not a card which is unique for every individual who enroll or apply to get his/her Aadhaar number. Aadhaar is not a compulsory approach instead, it is voluntary based and any individual who is interested in having Aadhaar number for himself/herself can enrol or apply to get Aadhaar number.