Aadhaar is a unique Identification number issued by UIDAI((Unique Identification Authority of India) to individuals for the purpose of establishing 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. The Unique Identification Authority of India (UIDAI) is the regulatory body for this.
Aadhaar is meant for individuals of any age (including children) for the purpose of establishing identities. Since Aadhaar is for only individuals, it is different for all the members of a family. For deciding uniqueness of every individual, the demographic details (residence address information) of the person and his/her biometric information (photograph, iris-scan, fingerprints) is collected which is stored in a centralized database.
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 enroll or apply to get Aadhaar number.
An individual will be provided with only one unique Aadhaar number and not multiple unique ID numbers. Aadhaar number will be valid for the whole life of any individual and does not need to be changed or renewed from time-to-time.
A person can get his/her Aadhaar number for free of cost.
The Aadhaar number can be used while opening a bank account, applying for passport, booking e-tickets and many other places where there is a need to give your identity.