For example, when the locale-sensitive date format service needs to format a date, it uses the convention appropriate to the current locale. The locale object also defines the concept of a default locale. The default locale is the locale, used by many programs, that regulates the rest of the computer's behavior by default and is usually controlled by the user in a control panel window. The locale mechanism does not require a program to know which locale the user is using and thus makes most programming simpler. Since locale objects can be passed as parameters or stored in variables, the program does not have to know specifically which locales they identify.
Many applications enable a user to select a locale.
The resulting locale object is passed as a parameter, which then produces the customized behavior for that locale. A locale provides a means of identifying a specific region for the purposes of internationalization and localization. ICU locales do not specify the encoding and specify variant locales differently. The languages are specified using a two-letter lowercase code for a particular language. There are often different language conventions within the same language.