What is UID?

Last Updated: 3 Oct 2025

A Unique Identification is merely a string assigned to an entity that identifies the entity uniquely.The Unique Identification Authority of India (UIDAI) plans to assign a Unique ID to every person residing in India. Biome-tric identification system and checks would be used to ensure that each individual is as-signed one and only UID and the process of generating a new UID would ensure that duplicates are not issued as valid UID numbers.

What is UIDAI?

The Unique Identification Authority of India (UIDAI) has been created, with the mandate of providing a unique identity to all Indian residents. The UIDAI has published an approach to pursuing this mandate, and plans to use biometrics to eliminate duplicates and ensure uniqueness at enrolment. Specifically, the UID number means a 12-digit numeric code that uniquely identifies every Indian resident within the Aadhaar system.

The AADHAR system is being designed to eventually service the entire population of India, and will involve the biometric identification of 1.2 billion residents. Since the estimated database size (1.2 Billion residents) is an order of magnitude larger than the current largest biometric database (115 Million), the biometric subsystem will have to be constantly monitored for accuracy, scalability and performance. To de-risk the entire program, the system will operate multiple concurrent solutions with the ability to introduce and test newer solutions.

Each Automated Biometric Identification Subsystem (ABIS) must implement an interface that is compliant with this specification. That de-couples the biometric subsystem from the main application logic, and enables a management layer that can orchestrate across the multiple solution providers, continuously measure accuracy, performance and enable better decision making. Initially, the same interface will be used for enrolment and authentication. At a later time, authentication may be moved out to a separate sub-system for better scaling, and replication. More generally, as the UID database grows in size, the requirements of the biometric system may evolve, and implementers of this interface will have to keep up with them.

Who is heading UIDAI?

Nandan Nilekani is currently the Chairman of the Unique Identification Authority of India (UIDAI),which aims to provide a unique identification number for all residents of India in the rank and status of a Cabinet minister.

Nandan Nilekani was most recently the co-chairman of the board of directors of Infosys Technologies Limited, which he co-founded in 1981. Serving as director on the company’s board since its inception to July 2009, he has held various posts at Infosys, including chief executive officer and managing director, president, and chief operating officer.

Nilekani co-founded India’s National Association of Software and Service Companies (NASSCOM) as well as the Bangalore chapter of The IndUS Entrepreneurs (TiE). He is a member of the board of governors of the Indian Council for Research on International Economic Relations (ICRIER) and the president of NCAER (the premier, independent, applied economics research institute in India).

Born in Bangalore, Nilekani received his bachelor’s degree in electrical engineering from the Indian Institute of Technology Bombay. He was named the Corporate Citizen of the Year at the Asia Business Leaders Award (2004) organized by CNBC. In 2005 he received the prestigious Joseph Schumpeter prize for innovative services in economy, economic sciences and politics.

He was awarded one of India’s highest civilian honours, the Padma Bhushan, in 2006. In 2006 he was also named Businessman of the Year by Forbes Asia. Time magazine listed him as one of the 100 most influential people in the world in 2006 and 2009.

What Distinguishes The Aadhaar Card From UIDAI?

UIDAI vs Aadhaar highlights the distinction between the governing body and the identity it issues. The table below presents how they differ in functioning, purpose, interconnections, etc.

Aspect	Aadhaar Card	UIDAI (Unique Identification Authority of India)
Nature	Physical/documentary form (card)	Government organisation/body
Purpose	Serves as identity and address proof for Indian citizens	Designs, implements, and manages the Aadhaar infrastructure
Function	Used for various services such as opening bank accounts, filing taxes, and government schemes	Manages data security, regulatory framework, and infrastructure of Aadhaar
Issuance	Issued by UIDAI to residents of India	Responsible for issuing and verifying Aadhaar numbers

What Are The Uses Of UIDAI Aadhaar?

The UIDAI Aadhaar serves as a crucial tool for identification verification and it is widely used across multiple sectors of India. Some of its main uses include:

• Proof of Identity and Address: Aadhaar can be considered a legitimate document to use when opening a bank account, applying for a passport or activating a new SIM card.
• Income Tax and PAN Linking: You’ve to link your Aadhaar with PAN for filing income tax returns or to prevent duplication or breach of any financial data.
• Digital Authentication: You can complete e-KYC (Know Your Customer) processes quickly to access necessary services such as applying for an LPG subsidy or taking out telecom services.
• Use in Education and Healthcare: Aadhaar is useful in speeding up the process for school admission or better access to healthcare schemes and services.

What is the process that will be followed to issue a UID number?

A resident will have to go to an enrolling agency, fill out an application form and provide the supporting documentation, including a photo and fingerprint, all ten fingerprints and both IRS scans.

The enrolling agency will collect this information and send the data, either singly or in batches, to the registrar, who will pass this on to the UID database.

The system will engage in a de-duplication exercise.

If the individual is not already in the database, a UID number will be issued and sent to the person at their residence. The UID number will also be sent to the Registrar for use in their service database.

If the individual is already in the database, the registration will be rejected and the person will be informed of the same.

The registrar will scan the supporting documentation and send it to the UIDAI and keep the physical copies with themselves.

What is the verification process that will be followed by the enrolling agency before processing the documents for a UID number?

A Demographic Data Fields Standards and Verification Procedure Committee under Mr. Vittal, ex-CVC, has submitted its report with respect to the verification procedure. The document is available on the website in the Documents section.

Will there be a card issued? How will the resident know what their number is?

No card will be issued by the UIDAI, but the resident will receive a letter from the UID authority giving the person the UID number and the information about the person that was collected. If there are any inaccuracies in the information, the person can correct them. There will be a tear-away portion in the letter that can act as a card for referencing the number. The registrar may issue a card for their purpose, in which they may include the UID number.

Why no card?

The UIDAI is focused on the identity of the person and not the identity document. The best match is the individual’s biometric, and a card cannot be a substitute. The UID can only establish a unique identity if authentication is done against the central database. Further, cards can be forged, stolen, faked, and the identity process diluted. While the UID authority only guarantees online authentication, the service providers are free to issue cards to people if it serves their purpose.

Frequently Asked Questions

1. What is the documentation needed to enrol in Aadhaar?

To get an Aadhaar card, you will be required to provide photocopies of your proof of identity, address and date of birth. In this aspect, the most accepted documents are a passport, a voter ID, a PAN card, or utility bills.

2. How long does it take to generate a UID?

After the registration of the Aadhaar is done, the hard copy of the card can take up to 90 days to arrive at your doorstep. Meanwhile, you can view your e-Aadhaar and download it via the UIDAI website once it is available.

3. Can I use my Aadhaar card as proof of address?

Yes, the Aadhaar card is acceptable as a valid identity and address card. Government offices, banks, and various service providers accept it as a document to be verified.

4. How do I update my UID details (like address or mobile number)?

If you wish to update your residential address, you must log in to the Self-Service Update Portal on the UIDAI website and rewrite it with the new address. To rectify the remaining details (such as mobile number, biometrics or demographic information), you would have to go to your nearest Aadhaar Enrolment/Update Centre along with the required documents.

5. How do I check the status of my Aadhaar enrolment?

The Aadhaar application can be tracked online using the 14-digit enrolment ID printed on your slip with the date and time of enrolment. This will tell you whether your Aadhaar has already been generated or not.

6. What is UID no.?

A UID number is a series of 12-digit unique codes assigned to every Indian who holds an Aadhaar card. It serves as a personal identity and is used in KYC processes when opening a bank account, requesting services, activating a new SIM card, etc.