World Library  
Flag as Inappropriate
Email this Article

Unique identifier

Article Id: WHEBN0003444411
Reproduction Date:

Title: Unique identifier  
Author: World Heritage Encyclopedia
Language: English
Subject: Identifier, Commercial and Government Entity code, MAC address, Message-ID, Publisher Item Identifier
Collection: Names, Universal Identifiers
Publisher: World Heritage Encyclopedia

Unique identifier

With reference to a given (possibly implicit) set of objects, a unique identifier (UID) is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose. There are three main types of unique identifiers, each corresponding to a different generation strategy:

  • serial numbers, assigned incrementally or sequentially
  • random numbers, selected from a number space much larger than the maximum (or expected) number of objects to be identified. Although not really unique, some identifiers of this type may be appropriate for identifying objects in many practical applications and are, with abuse of language, still referred to as "unique"
  • names or codes allocated by choice which are forced to be unique by keeping a central registry such as the EPC Information Services.

The above methods can be combined, hierarchically or singly, to create other generation schemes which guarantee uniqueness.

In many cases, a single object may have more than one unique identifier, each of which identifies it for a different purpose.

In relational databases, certain attributes of an entity that serve as unique identifiers are called primary keys.


  • Examples 1
    • National identification number 1.1
      • Aadhaar, the UID of India 1.1.1
    • Chemistry 1.2
    • Computing 1.3
    • Economics 1.4
    • Internet architecture and standards 1.5
    • Legal 1.6
    • Mathematical publications 1.7
    • Science 1.8
    • Transportation 1.9
  • References 2


National identification number

National identification number is used by the governments of many countries as a means of tracking their citizens, permanent residents, and temporary residents for the purposes of work, taxation, government benefits, health care, and other governance-related functions.

Aadhaar, the UID of India

Aadhaar is a 12-digit national identification number assigned to residents of India for lifetime. Its format is 1234-5678-9012 where the 11-digits are used as a sequence number and the rightmost 1-digit as an error detection check-sum digit. Aadhaar Number (AN) is not a proof of citizenship. It only guarantees identity; not rights, benefits or entitlements. Unique Identification Authority of India (UIDAI), a government agency, is the Registrar of Identities. It was established in January 2009 and commenced assigning AN from September 2010.[1]

As of April 2015, 814,495,057 AN have been assigned. In July 2014, this figure was 641,932,798. In September 2013, it was 416,992,803.[2]

Aadhaar is a digital identity, instantly verifiable online at the point of service (PoS), at any time, in a paperless way. The government hopes that it will enable under-privileged people to access social security benefits, which they have been deprived so far due to lack of proper identity.[3]




Internet architecture and standards


Mathematical publications




  1. ^
  2. ^ - and archived versions from Wayback Machine
  3. ^
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.