Updated: 09/12/2023 by Computer Hope

ID may refer to any of the following:

Identification card with clip.

1. In general, an ID is an abbreviation for identification. Identification is the act of being identified so a system can verify whom you say you are. For example, many services require a valid username and password before they can be accessed. If the correct username and password are entered, you are identified and can log in. Otherwise, you're not allowed access

2. With BSD (Berkeley Software Distribution), id is a command to show the numeric user and group ID on BSD. See our id command page for further information and examples on this command.

3. With CSS (cascading style sheets), id is a selector to specify a style on one HTML (hypertext markup language) element. For example, the "center" id below centers a paragraph of text. However, once an id is used on an element, it cannot be used with any other element. Use the class selector to use a style on more than one element.

CSS id code

#center { text-align: center; }

HTML <p> tag with center class

<p id="center">This text would be centered.</p>

This CSS code shows every CSS id is prefixed with a pound symbol before the id name. A line that does not begin with a pound is considered an HTML tag selector, and a class selector begins with a period.


Never start a CSS id with a number since not all browsers support id names beginning with numbers.

4. When describing a company, "id" is an abbreviation for id Software.

5. The Internet domain suffix .id is short for Indonesia.

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