ID

ID, I.D. or id may refer to:

Abbreviations

* Ibid (ibidem, Idem), a citation identifier for a source that was cited in the preceding endnote or footnote
* Identification
* Military and civilian neck-ID tags
** Identity card, a card used to establish positive identification of an individual
* Intelligent design, a modern form of the teleological argument (an argument for the existence of a god) which argues that life was designed
* Industrial design
* The Latin word "idem".

In codes

* Indonesia, ISO 3166-1 alpha-2 country code ID (Internet TLD: .id)
** Indonesian language, ISO 639 alpha-2 code id
* the United States postal abbreviation for Idaho
* Interlink Airlines, IATA airline code

In computer science

* Id (programming language) is a parallel functional programming language
* in the Objective-C programming language "id" is the designation of the generic object datatype
* id Software, the computer game software developer behind the Quake and Doom series, among others
* iD (video game), is a 1980s video game by Mel Croucher
* Internet Draft, a working document of the IETF

Places

* İd, town in Turkey

In popular culture

* i-D, a British fashion magazine
* I.D. (magazine), and American magazine focusing on Architecture, Graphic and Industrial Design
* I.D. (film), the 1995 British film, directed by Philip Davis
* iD Two, RTÉ television programme
* Investigation Discovery, an American cable channel which is abbreviated as "ID."

In mathematics

* Influence diagram, a graphical and mathematical representation of a decision situation
* Inside diameter, a dimension commonly used to specify the size of tubing or pipe
* An identity function, a function that always returns the same value that was used as its argument.

Other uses

* The "Citroën ID", a variant of the Citroën DS
* The Muslim religious festival of Id-ul-Fitr
* In Freudian psychology, id, ego, and super-ego are the three parts of the psychic apparatus
* Another spelling of Ide (fish)
* A non-standard Roman number form for the number 499
* I.D., a Doctor Who audio drama