The function of identification is to map a known quantity to an unknown entity so as to make it known. The known quantity is called the identifier (or Id) and the unknown entity is what needs identification. A basic requirement for identification is that the Id be unique. Ids may be scoped, that is, they are unique only within a particular scope. Ids may also be built out of a collection of quantities such that they are unique on the collective.

For data storage

Data storage device

thumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....

, identification is the capability to find, retrieve, report, change, or delete specific data

Data

The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...

 without ambiguity

Ambiguity

Ambiguity of words or phrases is the ability to express more than one interpretation. It is distinct from vagueness, which is a statement about the lack of precision contained or available in the information.Context may play a role in resolving ambiguity...

. This applies especially to information

Information

Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

 stored in database

Database

A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...

s. In database normalisation

Database normalization

In the design of a relational database management system , the process of organizing data to minimize redundancy is called normalization. The goal of database normalization is to decompose relations with anomalies in order to produce smaller, well-structured relations...

, it is the central, defining function to the discipline.

Example

To retrieve the data stored about an individual with the Internal Revenue Service

Internal Revenue Service

The Internal Revenue Service is the revenue service of the United States federal government. The agency is a bureau of the Department of the Treasury, and is under the immediate direction of the Commissioner of Internal Revenue...

 (IRS) of the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, the IRS needs to be supplied with the individual's Social Security number

Social Security number

In the United States, a Social Security number is a nine-digit number issued to U.S. citizens, permanent residents, and temporary residents under section 205 of the Social Security Act, codified as . The number is issued to an individual by the Social Security Administration, an independent...

 (SSN). The SSN, then, "identifies" a unique individual to the IRS. No other living person has that SSN, and that individual is assumed to not have more than one SSN. Other data that the individual's SSN identifies with the IRS would be such things as his or her name, birthdate, and current employer.

See also

• Authentication
  Authentication
  Authentication is the act of confirming the truth of an attribute of a datum or entity...
  
  
• Identification (disambiguation)
• Profiling
  Profiling
  Profiling, the extrapolation of information about something, based on known qualities, may refer specifically to:* Profiling practices * Forensic profiling, used in several types of forensic sciences* Offender profiling...
  
  
• Profiling practices
  Profiling practices
  Profiling refers to the whole process of construction and application of profiles generated by computerized profiling technologies. What characterizes profiling technologies is the use of algorithms or other mathematical techniques that allow one to discover patterns or correlations in large...