Aadhaar

Aadhaar is the name of India's identity-number programme and its digital identity infrastructure. UIDAI describes an Aadhaar number as a unique 12-digit number assigned to an individual after an enrolment process. Enrolment is based on demographic details and biometric information, with verification and de-duplication intended to avoid duplicate identities. Aadhaar is administered by the Unique Identification Authority of India (UIDAI), a statutory authority established under the Aadhaar (Targeted Delivery of Financial and Other Subsidies, Benefits and Services) Act, 2016.

UIDAI's enrolment guidance lists core demographic details such as name, date of birth, gender and address. It describes the biometric information collected for enrolment as a photograph, fingerprints and iris scans; mobile number and email are optional demographic details. Aadhaar is intended to provide a portable way to verify identity, including through online authentication. An Aadhaar number itself is a random identifier and is not designed to encode personal characteristics such as religion, caste or income.

Aadhaar authentication allows an authorised service to check an identity claim against UIDAI's system using permitted authentication methods. UIDAI describes uses in identity verification and electronic delivery of benefits and services. Aadhaar is an identity credential, not a guarantee that a person qualifies for a particular benefit: eligibility rules are determined by the relevant programme. The number is not proof of Indian citizenship or domicile, a distinction UIDAI explicitly makes. Having an Aadhaar number does not by itself grant a right to a government service or establish a person's legal status beyond identity.

The Aadhaar Act, 2016 provides the statutory framework for enrolment, authentication, use of information and oversight by UIDAI. The Act and related regulations have been amended over time. Accordingly, descriptions of permissible uses, retention and safeguards should be read against the current law and rules, rather than relying on summaries of the system's original design. The Supreme Court of India considered the constitutionality of the Aadhaar Act in K. S. Puttaswamy (Retd.) v. Union of India, issuing its decision on 26 September 2018.

In its 2018 decision, the Supreme Court upheld the Aadhaar Act's constitutional validity by majority while invalidating or reading down particular provisions. Among other holdings, the majority upheld Section 7's use of Aadhaar for certain state subsidies, benefits and services, while restricting mandatory use in some other contexts. The judgment also addressed private-sector authentication and data-retention provisions. The opinions included a dissent, so the ruling is not accurately captured by saying that the Court either simply approved every Aadhaar use or struck the entire programme down. The decision remains an important reference point for discussions about identity, privacy, proportionality and access to services.

Aadhaar's use of biometric and demographic data has prompted sustained debate about privacy, exclusion, security and the consequences of authentication failures. The 2018 litigation treated privacy as a constitutional issue and examined safeguards and the proportionality of specific uses. UIDAI publishes guidance on protecting Aadhaar information and offers services such as biometric locking and masked Aadhaar. Users should avoid publishing identity details unnecessarily and should use official UIDAI channels for authentication and updates. The existence of safeguards does not remove the need to assess how a particular institution uses Aadhaar or how people can access services when authentication is unavailable.

Aadhaar is a large-scale digital public identity infrastructure that can support identity checks and benefit delivery across different locations. Supporters emphasize portability and simplified verification; critics and courts have raised concerns about privacy, mandatory linking, exclusion and the scope of data use. These questions depend on the particular law, service and implementation. Aadhaar is therefore best understood both as an identification system and as a continuing subject of legal, administrative and public debate.